The authors thank Kerstin Glensk for preparing the MTases M.BseCI and Set7/9 and gratefully acknowledge funding by the Excellence Initiative of the German Federal and State Governments and RWTH Aachen University. The authors are happy to provide 6BAz and SeAdoYn or other cofactor analogues for collaborative research.

1. Genel Talimatlar <ol><li> Mağaza aziridin kofaktör (DMSO içinde) 6BAz ve protein MTase -80 ° C&#39;de Set7 / 9 ve çift aktif kofaktör SeAdoYn ve DNA MTase M.BseCI -20 ° C&#39;de (% 50 gliserol) da dahil olmak üzere diğer tüm reaktif maddeler. </li><li> Iyonu giderilmiş su içinde söndürme katsayısına ε 269nm (6BAz) = 16,000 cm -1 M 1 ve 260 nm ε (SeAdoYn) = 15.400 cm -1 M-1 kullanılarak UV / Vis spektroskopisi yoluyla 6BAz ve SeAdoYn konsantrasyonunu belirlemek. Tükenme katsayısı varsa 280 nm&#39;de absorpsiyon yoluyla doğrudan, Bradford tahlili ile MTases konsantrasyonunu belirlemek veya. </li><li> Enzim aktivitesinin kaybını önlemek için yoğun pipetle veya vorteks kabarcıkları oluşturarak önlemek için deneyin. Bunun yerine, yavaşça yukarı ve aşağı pipetleme karıştırın. </li><li> DMSO içindeki stok solüsyonlarından aziridin kofaktörleri eklerken deneyde nihai DMSO konsantrasyonu daha az olduğundan emin olmak% 5 daha. Her DNA ile spesifik olmayan reaksiyonları önlemek için, deney tamponu içerisinde 10 mM magnezyum tuzlarıdır. </li><li> Asidik stok çözümleri çift aktif kofaktörlerine eklerken pH değişiklikleri önlemek ve tahlil çözeltinin pH değeri önemli bir değişiklik olmadığından emin olmak için küçük hacimli (yüksek konsantre stok çözümleri) kullanın. , Gerekli bakır iyonu kompleks ile click reaksiyonunun etkilediği için bu deney tamponu içinde tioller, örneğin β-merkaptoetanol veya ditiyotreitol (DTT), kaçının. </li></ol> Aziridin kofaktörlerinin yoluyla DNA&#39;nın 2. Bir adım Etiketleme <ol><li> Sekans spesifik Metiltransferaz Bağlı Etiket ing M.BseCI DNA MTase ve aziridin kofaktör 6BAz ile plazmid DNA (gülümser). <ol><li> 20 ° C&#39;de kofaktör çözeltisi çözülme ve buz üzerinde tepkime karışımları hazırlamak. </li><li> Denemesine ek olarak herhangi bir spesifik olmayan modifikasyonlar ve An ve # görselleştirmek için bir &quot;Kofaktör&quot; kontrolünü gerçekleştirmek8220; Enzim &quot;kontrol, MTase hazırlık, doğal kofaktör AdoMet serbest olduğundan emin olmak için. </li><li> 10x değişiklik tamponu deney karışımı 2 ul için (100 mM Tris-HCl, içeren 100 mM MgCl2, 20 mM β-merkaptoetanol, pH 7.4) içinde, pBR322 (0.5 ug / ul), 10 eq 2 ul. DNA tanıma sekansı (pBR322 1 tanıma sekansı) ve 20 ul toplam hacim içinde 60 uM nihai konsantrasyona kadar aziridin kofaktör 6BAz başına M.BseCI. Kofaktör ve DNA MTase son ekleyin. NOT: β-merkaptoetanol, toksik korozif ve çevreye zarar vermektedir. </li><li> &quot;Kofaktör&quot; kontrol için yerine 6BAz deiyonize su ekleyin yerine M.BseCI ve &quot;enzim&quot; kontrolü için deiyonize su ekleyin. </li><li> Yavaşça yukarı ve aşağı pipetleme çözüm karıştırın. </li><li> 1 saat boyunca 55 ° C&#39;de inkübe edin. </li><li> Santrifüj kısaca tüplerinin altındaki tüm sıvıyı toplamak için. </li></ol></li><li> Kısıtlama-modifikasyon tahlil DNA modifikasyonu doğrulamak için. <ol><li> 80 ul deiyonize su ve 3.3 ul (100 mM Tris-HCl, 50 mM MgCl2, 1 M NaCl, 1 mg / ml sığır serumu albümini, pH 8.0 ihtiva eder) 10 ul 10x R.TaqI tampon karıştırılmasıyla bir çözelti hazırlayın kısıtlama endonükleaz Thermus aquaticus (artma) (R.TaqI, 10 U / ul). Son adımda artma eklemek için emin olun. </li><li> 2.1.7 Her tüpe R Taql tampon 10x 2 ul ve yukarıdaki (2.2.1) çözelti 28 ul ekle. </li><li> Yavaşça yukarı ve aşağı pipetleme çözüm karıştırın. </li><li> 30 dakika boyunca 65 ° C&#39;de inkübe edin. </li><li> Santrifüj kısaca tüplerinin altındaki tüm sıvıyı toplamak için. </li></ol></li><li> Streptavidin ile Elektromobilite kayma deneyi (EMSA) fonksiyonel değişiklik doğrulamak için. <ol><li> Her bir tüp (2.2.5) 25 ul çıkarın ve streptavidin m göre bir streptavidin çözeltisi (1 mM, 2.4 ulonomer 100 mM Na 2 HPO 4 içeren streptavidin tamponu, 100 mM NaCI, pH 7.5; Toplam biyotin 4 eşdeğer). Kalan tüpler streptavidin tamponu 2.4 ul ekleyin. </li><li> 1 saat boyunca 37 ° C&#39;de tüm tüpler inkübe edin. </li></ol></li><li> Agaroz jel elektroforez ile analizi. <ol><li> Her tüpe 6x yükleme tamponu (% 0.25 bromofenol mavisi,% 30 gliserol) içinde 5 ul ekle. </li><li> Yavaşça çözüm karıştırın. </li><li> Yük (bir 10,000X stok çözeltisinden 1x GelRed içeren 0.5x TBE tamponu içinde% 1 agaroz), bir agaroz jeli, kuyu içine her bir numune için 10 ul. </li><li> Yaklaşık 80 V ile 0.5x TBE tamponu jel çalıştırın. 1 saat. </li><li> Bir filtre (540 ± 50 nm) ile donatılmış bir CCD kamera ile UV tablosu (312 nm) DNA bantları gözünüzde canlandırın. NOT: UV ışık Gözleri ve cildi zarar vermektedir. </li></ol></li></ol> Çift Aktif kofaktörlerinin aracılığıyla 3. İki aşamalı Protein Etiketleme <ol><li> Methyltransfhiston H3 lizin 4 etiketleme (modifikasyon adım) için Set7 / 9 ve çift-aktif kofaktör SeAdoYn ile Aktif Gruplar (Mtag) Devri silmek-yöneltti. <ol><li> Bileşenleri çözülme ve buz üzerinde reaksiyon karışımları hazırlayın. NOT: Her zaman SeAdoYn bozulmasını önlemek için soğutulmuş tutun. </li><li> Denemesine ek olarak herhangi bir spesifik olmayan değişiklikler görselleştirmek için bir &quot;Kofaktör&quot; kontrol gerçekleştirmek ve bir &quot;enzim&quot; kontrol, flüoresan probun spesifik olmayan reaksiyonlar ortaya çıkarmaktır. </li><li> Bir deney çözeltisi (20 ul) modifikasyon tamponu (50 mM Tris-HCl,% 5 gliserol, pH 8.5), 10 uM histon H3, uM Set7 / 9 10 ve 600 uM SeAdoYn (selenyum hem de epimerler karışımı) ihtiva eden hazırlayın. Son adımda daha sonra maddeyi ve MTase ekleyin. </li><li> &quot;Kofaktör&quot; kontrol için 3.1.3 gibi bir tahlil çözelti hazırlamak ve sentetik kofaktör ile rekabet etmek 60 mM AdoMet ekleyin. &quot;Enzim&quot; kontrol için yerine SeAdoYn deiyonize su ekleyin.</li><li> Yavaşça yukarı ve aşağı pipetleme çözüm karıştırın. PH şerit (- 10 pH aralığı 5) üst alanında her solüsyonun 1 ul ekleyerek pH değerini kontrol edin. </li><li> 2 saat süre ile 37 ° C&#39;de inkübe edilir. </li><li> Bu arada, bir% 12 SDS-poliakrilamid jel hazırlamak (çalışma jelde: 357 mM Bis-Tris pH 6,5-6,8,% 0.1 (a / h) APS ağırlık,% 0.04 (h / h) TEMED ve% 12 akrilamid / bisakrilamid 37.5: 1 ; yükleme jel: 357 mM Bis-Tris 6,5-6,8 pH,% 0.1 APS (w / v),% 0.04 (h / h) TEMED,% 5 akrilamid / bisakrilamid 37.5: 1). NOT: Akrilamid / bisakrilamid tehlikeli toksik ve sağlıktır. Bu işlem sırasında eldiven giyin. </li></ol></li><li> Bakır-katalize azid-alkin sikloadisyonu (CuAAC) (etiketleme adım) üzerinden histon H3 alkinylated lizin 4 Kimyasal etiketleme. <ol><li> Sadece modifikasyonu tepkime sonuna kadar 3 mM CuSO 4, 3 mM tris (3-hidroksipropil-triazolilmetil) amin (THPTA), 250 mM sodyum askorbat ve 6 mM TAMRA azit içeren 5x tıklama karışımı hazırlamak20 ul toplam hacim. </li><li> CuAAC başlatmak ve değiştirme reaksiyonu durdurmak için her bir tüpe, taze hazırlanmış 5x tıklama karışımı 5 ul ekle. </li><li> Yukarı ve aşağı pipetleme hafifçe karıştırın. </li><li> Floroforun fotoğraf beyazlatma önlemek için ışık alüminyum folyo ile tüm tüpleri koruyun. </li><li> 1 saat boyunca 20 ° C&#39;de inkübe edilir. </li></ol></li><li> Protein yağış ücretsiz TAMRA floroforun fazlalığını ortadan kaldırmak için. <ol><li> 34 - bedava TAMRA floroforun yoğun olarak-jel floresan floresan etiketli histon H3 outshining önlemek için, proteinler (3.3.4 3.3.2) yağış fazlalığı floroforu çıkarın. </li><li> 75 ul metanol, 18.8 ul kloroform ve kısa bir süre için her eklemeden sonra her tüp ve vorteks deiyonize su 50 ul ekle. 5 dakika boyunca 16,000 x g&#39;de santrifüjleyin. Protein içeren arayüz katmanı, bozmadan üst faz çıkarın. </li><li> Kalan faz 56.3 ul Metanol In 5 dakika boyunca 16.000 xg&#39;de her tüp, girdap ve santrifüj protein pelet. Süpernatantı. Pelet yıkamak için bu adımı tekrarlayın. </li><li> Tüy bırakmayan bir doku ile açık tüpler Kapak ve 15 saat kurumaya bırakın - 30 dakika. </li></ol></li><li> SDS PAGE yoluyla analizi. <ol><li> (20 ul SDS yükleme tamponu (50 mM Tris-HCI,% 2.5 (ağ / hac) SDS,% 10 (h / h) gliserol, 320 mM β-merkaptoetanol ve% 0.05 3.3.4 çökeltilir proteinleri çözülür w / V) bromfenol mavisi, pH 6.8). Tamamen bir pipet ile tüplerin duvarları durulama pelet çözmek için emin olun. </li><li> 10 dakika boyunca 95 ° C&#39;de inkübe edin ve bunları 20 ° C&#39;ye kadar soğumaya bırakın. </li><li> Santrifüj kısaca tüplerinin altındaki tüm sıvıyı toplamak için. </li><li> Bir SDS poliakrilamid jeli (3.1.7) oyuklarına Her numunenin bütün miktarı yerleştirin. 50 mM MOPS, 50 mM Tris-X (Tris-bazlı), 5 mM EDTA,% 0.1 kullanarak (a / h) elektroforez için tampon olarak SDS aktarıldı. </li><li>Yaklaşık 120 V ile jel çalıştırın. 90 dakika. </li><li> Bir filtre (50 nm ± nm 540) ile donatılmış bir CCD kamera ile UV tablosu (312 nm) üzerinde-jel floresan gözünüzde canlandırın. NOT: UV ışık Gözleri ve cildi zarar vermektedir. </li></ol></li></ol>

The authors disclose the following competing financial interest: E.W. is inventor on related patents.

DNA MTases ve aziridin cofactors (gülümseyen DNA) ile DNA Bir adım etiketleme sağlam bir yöntemdir, ancak deney planlarken bazı yönleri dikkate alınmalıdır. Aziridin kofaktör: M.BseCI DNA etiketleme için 6BAz konsantrasyonu 60 uM idi. Diğer DNA MTases kullanırken kofaktör konsantrasyonu düşük 20 gibi uM DNA MTase M.TaqI 19 kullanılmıştır, örneğin konsantrasyonları optimize edilmelidir. Düşük 6BAz konsantrasyonları streptavidin (tahlil...

Nükleik asitler ve proteinlerin 1,2 3,4 Özgül etiketleme fonksiyonel karakterizasyonlar, tıbbi teşhis ve (nano) biyoteknoloji için önemli ilgi alanıdır. Burada S -adenosyl-L-metionin (AdoMet veya SAM) bağlı metiltransferaz (MTases) dayanır, bu biyopolimerler için enzimatik bir etiketleme yöntemi sunulmaktadır. Bu enzim sınıfının (EC 2.1.1.), Nükleik asitlerin ve proteinlerin belirli artıkların tek tek nükleofilik pozisyonlar (nitrojen, oksijen, kükürt ve karbon atomu) yönelik olarak ve doğal olarak kofaktör AdoMet (Şekil 1A) 5 aktive metil grubunu aktarır. Buna ek olarak, MTases afinite etiketleri, floroforlar veya diğer etiketler (Şekil 1B) 6 belirli etiketleme için sentetik kofaktör analoglarını kullanabilir. AdoMet analoglarının iki sınıfı geliştirilmiştir: S Sequence özgü M ethyltransferase- I Aziridin kofaktörleri </strong&gt; Nduced L abel ing (gülümseyerek) 7 ve A ctivated G grupların aldığı m ethyltransferase-yönettiği T ransfer çift aktive AdoMet analogları (Mtag) 8. <img alt="Şekil 1," fo:content-width="7in" src="/files/ftp_upload/52014/52014fig1highres.jpg" width="700" /> Şekil 1.:. Metiltransferaz (MTases), DNA, RNA, proteinler ve küçük biyomoleküller dahil olmak üzere çeşitli yüzeyler için doğal kofaktör AdoMet (SAM) A. Metil grup transfer nükleik asitlerin ve proteinlerin B. Etiketleme / işlevselleştirme (NNNNN = katalize reaksiyonlar proteinler için RNA, ve amino asitler için temel DNA çiftleri, nükleotitler sentetik kofaktör analogları ile yeşil hedef tortu) ile MTase xxxxx = tanıma sekansı. Bir raportör grubu içeren Aziridin kofaktör (mavi küre)özellikle de hedef tortu (sol) ve iki aktif AdoMet analogları ile birlikte dizi adenin halkası olan bağlı bir ikinci aşamada bioorthogonal Click reaksiyonu ile etiketlenebilir, bir kimyasal raportör Y (sağ) taşıyan uzatılmış alkil zincirlerinin aktarmak yol açar. <a href="https://www.jove.com/files/ftp_upload/52014/52014fig1highres.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> Aziridin kofaktör DNA MTases en iyi çalışır. Bir azot atomu 9 (veya bunun bir N 10,11 -mustard) yerine, sülfonyum merkezi olarak bir reaktif grup ile üç unsurlu bir halka ihtiva etmektedir. Bu nitrojen atomu protonlanma DNA ile bütün kofaktör bağlanması kovalent neden hedef nükleotid nükleofilik saldırı aziridin halkası aktive eder. Adenin halkasına raportör grupları takılarak aziridin kofaktörler (bir aşamada DNA etiket DNA MTases ile kombinasyon halinde de kullanılabilir <stron<html> g&gt; Sol Şekil 1B) 7,12. 15 (adenin halkasının 6 konumuna bağlı biyotin ile aziridin kofaktör) ve Bacillus stearothermophilus&#39;dan adenin özgü DNA MTase (M.BseCI) 16 (Şekil 2 - Bu 6BAz 13 DNA biyotinilasyon için detaylı olarak gösterilmektedir ) DNA&#39;nın Bir adım etiketleme aziridin kofaktörlerinin yoluyla: protokol bölümüne 2 bkz. Haemophilus heamolyticus gelen M.BseCI (5&#39;-ATCG T-3 &#39;tanıma sekansı), yani Thermus aquaticus (M.TaqI, 5&#39;-TCG bir -3 DNA MTases&#39;), ek olarak (M.HhaI, 5 &#39;-G Cı GC-3&#39;) ve Spiroplasma (M.SssI gelen 5&#39;-C G-3 &#39;), başarılı bir şekilde 6BAz 17 ile DNA biotinylate için kullanılmıştır. Ayrıca, aziridin kofaktörler tek aşamalı floresan DNA etiketleme 18,19 için kullanılabilecektir. ontent &quot;fo: keep-together.within-sayfa =&quot; always &quot;&gt; <img alt="Şekil 2," fo:content-width="7in" src="/files/ftp_upload/52014/52014fig2highres.jpg" width="700" /> Şekil 2:. M.BseCI ve 6BAz ile DNA sekansa özel tek-aşamalı biyotinilasyon DNA MTase M.BseCI çift bükümlü DNA dizisi 5&#39;-ATCG T-3 &#39;tanır ve doğal olarak, ikinci adenin amino grubunun metile Kalıntı (yeşil) AdoMet kullanarak. Aziridin kofaktör 6BAz ile reaksiyona ders değiştirilir ve M.BseCI hedef adenin ile biyotin (mavi) dahil olmak üzere tüm kofaktör birleştirilmesi ile spesifik DNA biyotinilasyonunu sırası yol açar. <a href="https://www.jove.com/files/ftp_upload/52014/52014fig2highres.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> Çift aktif AdoMet analogları doymamış yan zincirleri yerine sülfonyum merkezinde bir metil grubunu (Şekil 1B genişletilmiş içeren </strong&gt;, sağ) 20. sülfonyum merkezine β-konumunda doymamış çift veya üçlü bağ elektronik konjugatif istikrar ile geçiş devlet içinde olumsuz etkileri sterik dengeler. Sülfonyum merkezi ve doymamış bağ hem de enzimatik transferi için yan zinciri etkinleştirmek için, bu kofaktör çift aktive AdoMet analogları adlandırılmıştır. Tipik haliyle, bir ikinci aşamada 8,21 olarak kemo-seçici etiketleme, amino, alkin ve asit grupları gibi benzersiz kimyasal grupların (kimyasal muhabir) ile yan zincirleri aktarmak için kullanılır. RNA ve protein ek etiketleme sağlayan 28 - Genel olarak, iki aktif AdoMet analogları RNA MTases 22,23 DNA MTases 8,20,21 için değil, aynı zamanda yardımcı faktörler ve protein MTases 24 gibi yalnızca işlev görebilir. Ancak, genişletilmiş yan zincirler sterik daha bir metil grubu daha zorlu ve mühendislik sık sık bir protein MTase aktif siteleri büyütme vardırtr verimli aktarım hızları elde etmek için gerekli. Bakır kimyasal değişiklikler aşağıdaki için enzimatik transferi sırasında geçiş devletin 1. Sabitleme ve 2. reaktif kolu: Bu sorunun başka bir çözüm, küçük bir propargil terminali alkin iki fonksiyonu vardır grup (üç karbon) ile bir AdoMet analog kullanmak için katalize azid-alkin sikloadisyonu (CuAAC) kimyasını tıklayın. Bu Oluşan proparjilik AdoMet analog 29 nötr veya hafif bazik koşullar altında ve sadece sınırlı kullanımı oldukça kararsız olduğu ortaya çıktı. Bu dezavantajı selenyum ile kükürt atomu yerine sabit olabilir. Elde edilen kofaktör 5 &#39;- [(Se) [(3 S) -3-amino-3-karboksipropil] prop-2-ynylselenonio] -5&#39;-deoksiadenozin (SeAdoYn, Şekil 3) ile, vahşi tip DNA tarafından kabul edilir, RNA, ve protein MTases 30 - birçok durumda protein mühendisliği ihtiyacını ortadan kaldırmaz 32. Bu floresan pro ile tarif edilmektedir<html> histon H3 lizin ile tein etiketleme 4 (H3K4) MTase Set7 / 9 33 (: çift aktif kofaktör aracılığıyla İki aşamalı protein etiketleme Şekil 3, protokol bölümüne 3). <img alt="Şekil 3," fo:content-width="7in" src="/files/ftp_upload/52014/52014fig3highres.jpg" width="700" /> Şekil 3:. Set7 / 9 histon H3 diziye özel iki-aşamalı floresan etiketleme, SeAdoYn ve TAMRA azid proteini MTase Set7 / 9 doğal AdoMet ile histon H3 lizin 4 amino grubunun (H3K4, yeşil) bileşi. Çift aktif kofaktör ile SeAdoYn MTase lisin kalıntıya küçük bir propargil grubu (kırmızı) aktarır. bağlı uç üçlü bağ daha sonra seçici azid türevlendirilmemiş TAMRA (tetrametilrodamin, mavi) florofor ile bioorthogonal click reaksiyonunun (bakır ile katalize edilen azit-alkin siklo, CuAAC) değiştirilir.yük / 52.014 / 52014fig3highres.jpg &quot;target =&quot; _ blank &quot;&gt; bu rakamın daha büyük bir versiyonunu görmek için burayı tıklayınız.

<table border="0" cellpadding="0" cellspacing="0" width="669">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Name of Reagent/ Equipment</td>
			<td style="width:139px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">6BAz</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Synthesized according to Weinhold et al., Patent number US 8,129,106, published March 6, 2012.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">&#946;-Mercaptoethanol</td>
			<td style="width:139px;">Serva</td>
			<td align="right" style="width:119px;">28625</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Acetic acid</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td align="right" style="width:119px;">10304980</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Acrylamide/Bis Solution, 37.5:1</td>
			<td style="width:139px;">Serva</td>
			<td align="right" style="width:119px;">10688</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">UltraPure Agarose</td>
			<td style="width:139px;">Invitrogen</td>
			<td align="right" style="width:119px;">16500100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Ammonium persulfate (APS)</td>
			<td style="width:139px;">Serva</td>
			<td align="right" style="width:119px;">13375</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Bis-Tris</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1304</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Boric acid</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1115</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Bromophenol blue Na salt</td>
			<td style="width:139px;">Serva</td>
			<td align="right">15375</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Copper(II) sulfate</td>
			<td style="width:139px;">Aldrich</td>
			<td style="width:119px;">C1297</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Chloroform</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td align="right">10020090</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Coomassie Brilliant Blue</td>
			<td style="width:139px;">Serva</td>
			<td align="right" style="width:119px;">17525</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">EDTA disodium salt</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Ethanol</td>
			<td style="width:139px;">Merck</td>
			<td align="right" style="width:119px;">100983</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">GelRed (10000x in water)</td>
			<td style="width:139px;">Biotium</td>
			<td align="right" style="width:119px;">41003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Glycerol (99.5%)</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">2006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">FastRuler Low Range DNA Ladder</td>
			<td style="width:139px;">Thermo Scientific</td>
			<td style="width:119px;">SM1103</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Histone H3</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Expressionplasmid obtained from Dr. Philipp Voigt and Prof. Danny Reinberg; expression and isolation according to T. J. Richmond et al., J. Mol. Biol. 1997, 272, 301-311.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">M.BseCI</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Expressionplasmid obtained from Dr. Michael Kokkinidis; expression and isolation according to Kapetaniou et al., Acta Cryst. 2006, F63, 12-14.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Methanol</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td align="right" style="width:119px;">10675112</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Magnesiumchloride&#160; hexahydrate</td>
			<td style="width:139px;">J.T. Baker</td>
			<td align="right" style="width:119px;">4003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">MOPS</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1081</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Sodium chloride</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1112</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">pH strip (Neutralit)</td>
			<td style="width:139px;">Merck</td>
			<td align="right" style="width:119px;">1,095,330,001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">pBR322</td>
			<td style="width:139px;">Thermo Scientific</td>
			<td style="width:119px;">SD0041</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">R.TaqI (10u/&#181;l)</td>
			<td style="width:139px;">Thermo Scientific</td>
			<td>ER0671</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">SeAdoYn</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Synthesized according to Willnow et al., ChemBioChem 2012, 13, 1167-1173.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Set7/9</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Expressionplasmid obtained from Prof. Danny Reinberg, expression and isolation according to D. Reinberg et al., Genes Dev.2002, 16, 479-489.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Streptavidin</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">3058</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">(+)-Sodium L-ascorbate</td>
			<td style="width:139px;">Sigma Life Science</td>
			<td style="width:119px;">A7631</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">SDS Granular</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1833</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">di-Sodiumhydrogenphosphat</td>
			<td style="width:139px;">Merck</td>
			<td align="right" style="width:119px;">106,586</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">TAMRA-azide</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">TaqI buffer (10x)</td>
			<td style="width:139px;">Thermo Scientific</td>
			<td style="width:119px;">B28</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:245px;">N,N,N&#39;,N&#39;-Tetramethylethylenediamine (TEMED)</td>
			<td style="width:139px;">Acros Organics</td>
			<td align="right" style="width:119px;">42058</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Tris-HCl</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1028</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Tris-X (TRIS-base)</td>
			<td style="width:139px;">Gerbu</td>
			<td align="right" style="width:119px;">1018</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:245px;">Tris(3-hydroxypropyltriazolyl-methyl)amine (THPTA)</td>
			<td style="width:139px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">762342</td>
			<td></td>
		</tr>
	</tbody>
</table>

sequence-specific labeling of nucleic acids and proteins with methyltransferases and cofactor analogues

S -Adenosyl-L-metionin (AdoMet veya SAM) bağlı metiltransferaz (MTase) DNA, RNA, proteinler ve küçük biyomoleküller belirli konumlara AdoMet aktive metil grubu transferini katalize eder. Bu doğal metilasyon reaksiyonu sentetik kofaktör analoglarını kullanarak alkilasyon reaksiyonları de çok çeşitli genişletilebilir. Bir aziridin halkası ile AdoMet reaktif sülfonyum merkezi değiştirilmesi çeşitli DNA MTases ile DNA ile birleştirilebilir kofaktörler yol açar. Bu aziridin kofaktörler adenin parçasının farklı pozisyonlarda raportör grup ile donatılmıştır ve DNA (Smiling DNA) L Abel ing nduced ethyltransferase- S Sequence özgü M kullanılabilir. Tipik bir örnek olarak, DNA MTase M.BseCI ve aziridin kofaktör 6BAz içinde olan 5&#39;-ATCG T-3 &#39;dizisi bir pBR322 plazmid DNA biyotinilasyon için bir protokol eldebir adım. Bir ctivated G grupların aldığı (Mtag) m ethyltransferase-yönettiği T ransfer için kullanılan AdoMet benzerlerinin başka bir sınıf doymamış alkil grupları sonuçları ile aktive edilmiş bir metil grubunun çıkarılması. Uzun yan zincirler sülfonyum merkezi ve doymamış bağ ile aktive olduğundan, bu kofaktörler çift aktif AdoMet analogları olarak adlandırılır. Bu analoglar aziridin kofaktörlerinin gibi DNA MTases için kofaktör olarak işlev, aynı zamanda RNA, protein ve küçük molekül MTases için değil sadece. Bunlar tipik olarak ikinci bir kimyasal aşama raportör grup ile etiketlenmiş olan eşsiz fonksiyonel gruplarla MTase substratların enzimatik modifikasyonu için kullanılır. Bu histon H3 proteinin floresan etiketlemesi için bir protokol örneklenmiştir. Küçük bir propargil grubu tıklama etiketleme ardından histon H3 lizin 4 (H3K4) MTase Set7 / 9 ile proteine ​​kofaktör analog SeAdoYn aktarılırTAMRA azit ile alkynylated histon H3. Kofaktör analoglarıyla MTase aracılı etiketleme tanımlanması ve fonksiyonel çalışma MTase alt tabakalar hem de DNA genotiplemesi ve metilasyon tespiti de dahil olmak üzere pek çok verici uygulama için elverişli bir teknolojidir.

Aziridin kofaktörlerinin yoluyla DNA&#39;nın Bir adım Etiketleme Bu örnek, reaksiyon, çift kollu bir 5&#39;-ATCG T-3 &#39;dizisi içindeki ikinci adenin kalıntısı değiştirir ve pBR322 plazmidi (Şekil 4A) ilgili bir tanıma sitesi vardır DNA MTase M.BseCI ile gerçekleştirilir. Plazmid etiketleme test etmek için, pBR322 kısıtlama endonükleaz (artma) R.TaqI (5&#39;-TCGA-3 &#39;) ile tehdit edildi. R.TaqI M.BseCI sitede yer alan bunlar...

Watch this Scientific Journal Video about Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues at JoVE.com

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues

DNA ve proteinler dizi-spesifik afinite ya da DNA ya da protein Methyltransferases sentetik kofaktör analogları kullanılarak flüoresan raportör grup ile etiketlenir. Enzimler, aziridin veya çift aktif kofaktör benzerlerinin kofaktör özelliğine göre bir veya iki adım etiketleme için kullanılmaktadır.

Methyltransferases ve Kofaktör Analoglarının ile Nükleik Asitler ve Proteinler Dizi-spesifik Etiketleme

S-Adenosyl-l-methionine (AdoMet or SAM)-dependent methyltransferases (MTase) catalyze the transfer of the activated methyl group from AdoMet to specific ...

sequence-specific-labeling-nucleic-acids-proteins-with

Research

JoVE Journal

Biology

13.9K Görüntüleme.  RWTH Aachen University.  DNA ve proteinler dizi-spesifik afinite ya da DNA ya da protein Methyltransferases sentetik kofaktör analogları kullanılarak flüoresan raportör grup ile etiketlenir. Enzimler, aziridin veya çift aktif kofaktör benzerlerinin kofaktör özelliğine göre bir veya iki adım etiketleme için kullanılmaktadır. 

Video: Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues

Immunofluorescent Detection of Two Thymidine Analogues (CldU and IdU) in Primary Tissue

Accurate measurement of cell division is a fundamental challenge in experimental biology that becomes increasingly complex when slowly dividing cells are analyzed. Established methods to detect cell division include direct visualization by continuous microscopy in cell culture, dilution of vital dyes such as carboxy&#64258;uorescein di-aetate succinimidyl ester (CFSE), immuno-detection of mitogenic antigens such as ki67 or PCNA, and thymidine analogues. Thymidine analogues can be detected by a variety of methods including radio-detection for tritiated thymidine, immuno-detection for bromo-deoxyuridine (BrdU), chloro-deoxyuridine (CldU) and iodo-deoxyuridine (IdU), and chemical detection for ethinyl-deoxyuridine (EdU). We have derived a strategy to detect sequential incorporation of different thymidine analogues (CldU and IdU) into tissues of adult mice. Our method allows investigators to accurately quantify two successive rounds of cell division. By optimizing immunostaining protocols our approach can detect very low dose thymidine analogues administered via the drinking water, safe to administer to mice for prolonged periods of time. Consequently, our technique can be used to detect cell turnover in very long-lived tissues. Optimal immunofluoresent staining results can be achieved in multiple tissue types, including pancreas, skin, gut, liver, adrenal, testis, ovary, thyroid, lymph node, and brain. We have also applied this technique to identify oncogenic transformation within tissues. We have further applied this technique to determine if transit-amplifying cells contribute to growth or renewal of tissues. In this sense, sequential administration of thymidine analogues represents a novel approach for studying the origins and survival of cells involved in tissue homeostasis.

Immunofluorescent Detection of Two Thymidine Analogues CldU and IdU in Primary Tissue

We have derived a strategy to detect sequential incorporation of thymidine analogues (CldU and IdU) into tissues of adult mice to quantify two successive rounds of cell division. This strategy is useful to detect cell turnover of long-lived tissues, oncogenic transformation, or transit-amplifying cells.

İlköğretim Doku İki timidin analogları Immunofluorescent Algılama (CldU ve IDU)

Accurate measurement of cell division is a fundamental challenge in experimental biology that becomes increasingly complex when slowly dividing cells are ...

Biyoloji

Profiling of Methyltransferases and Other S-adenosyl-L-homocysteine-binding Proteins by Capture Compound Mass Spectrometry (CCMS)

There is a variety of approaches to reduce the complexity of the proteome on the basis of functional small molecule-protein interactions such as affinity chromatography 1 or Activity Based Protein Profiling 2. Trifunctional Capture Compounds (CCs, Figure 1A) 3 are the basis for a generic approach, in which the initial equilibrium-driven interaction between a small molecule probe (the selectivity function, here S-adenosyl-L-homocysteine, SAH, Figure 1A) and target proteins is irreversibly fixed upon photo-crosslinking between an independent photo-activable reactivity function (here a phenylazide) of the CC and the surface of the target proteins. The sorting function (here biotin) serves to isolate the CC - protein conjugates from complex biological mixtures with the help of a solid phase (here streptavidin magnetic beads). Two configurations of the experiments are possible: "off-bead" 4 or the presently described "on-bead" configuration (Figure 1B). The selectivity function may be virtually any small molecule of interest (substrates, inhibitors, drug molecules).
S-Adenosyl-L-methionine (SAM, Figure 1A) is probably, second to ATP, the most widely used cofactor in nature 5, 6. It is used as the major methyl group donor in all living organisms with the chemical reaction being catalyzed by SAM-dependent methyltransferases (MTases), which methylate DNA 7, RNA 8, proteins 9, or small molecules 10. Given the crucial role of methylation reactions in diverse physiological scenarios (gene regulation, epigenetics, metabolism), the profiling of MTases can be expected to become of similar importance in functional proteomics as the profiling of kinases. Analytical tools for their profiling, however, have not been available. We recently introduced a CC with SAH as selectivity group to fill this technological gap (Figure 1A).
SAH, the product of SAM after methyl transfer, is a known general MTase product inhibitor 11. For this reason and because the natural cofactor SAM is used by further enzymes transferring other parts of the cofactor or initiating radical reactions as well as because of its chemical instability 12, SAH is an ideal selectivity function for a CC to target MTases. Here, we report the utility of the SAH-CC and CCMS by profiling MTases and other SAH-binding proteins from the strain DH5&alpha; of Escherichia coli (E. coli), one of the best-characterized prokaryotes, which has served as the preferred model organism in countless biochemical, biological, and biotechnological studies. Photo-activated crosslinking enhances yield and sensitivity of the experiment, and the specificity can be readily tested for in competition experiments using an excess of free SAH.

Profiling of Methyltransferases and Other S-adenosyl-L-homocysteine-binding Proteins by Capture Compound Mass Spectrometry CCMS

Capture Compounds are trifunctional small molecules to reduce the complexity of the proteome by functional reversible small molecule-protein interaction followed by photo-crosslinking and purification. Here we use a Capture Compound with S-adenosyl-L-homocysteine-binding as selectivity function to isolate methyltransferases from an Escherichia coli whole cell lysate and identify them by MS.

Methyltransferases, profilleme ve Diğer S Adenosil- L</subYakalama Bileşik Kütle Spektrometresi (CCMS)> homosistein bağlayıcı Proteinler

There is a variety of approaches to reduce the complexity of the proteome on the basis of functional small molecule-protein interactions such as affinity ...

NanoDrop Microvolume Quantitation of Nucleic Acids

Biomolecular assays are continually being developed that use progressively smaller amounts of material, often precluding the use of conventional cuvette-based instruments for nucleic acid quantitation for those that can perform microvolume quantitation.
The NanoDrop microvolume sample retention system (Thermo Scientific NanoDrop Products) functions by combining fiber optic technology and natural surface tension properties to capture and retain minute amounts of sample independent of traditional containment apparatus such as cuvettes or capillaries. Furthermore, the system employs shorter path lengths, which result in a broad range of nucleic acid concentration measurements, essentially eliminating the need to perform dilutions. Reducing the volume of sample required for spectroscopic analysis also facilitates the inclusion of additional quality control steps throughout many molecular workflows, increasing efficiency and ultimately leading to greater confidence in downstream results.
The need for high-sensitivity fluorescent analysis of limited mass has also emerged with recent experimental advances. Using the same microvolume sample retention technology, fluorescent measurements may be performed with 2 &mu;L of material, allowing fluorescent assays volume requirements to be significantly reduced. Such microreactions of 10 &mu;L or less are now possible using a dedicated microvolume fluorospectrometer.
Two microvolume nucleic acid quantitation protocols will be demonstrated that use integrated sample retention systems as practical alternatives to traditional cuvette-based protocols. First, a direct A260 absorbance method using a microvolume spectrophotometer is described. This is followed by a demonstration of a fluorescence-based method that enables reduced-volume fluorescence reactions with a microvolume fluorospectrometer. These novel techniques enable the assessment of nucleic acid concentrations ranging from 1 pg/ &mu;L to 15,000 ng/ &mu;L with minimal consumption of sample.

The use of NanoDrop microvolume systems as practical and efficient alternatives to traditional nucleic acid quantitation methodology is described through the demonstration of two microvolume nucleic acid quantitation protocols.

Nükleik Asitlerin NanoDrop Microvolume kantitasyonu

Biomolecular assays are continually being developed that use progressively smaller amounts of material, often precluding the use of conventional ...

Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling

Two electrode voltage clamp electrophysiology (TEVC) is a powerful tool to investigate the mechanism of ion transport1 for a wide variety of membrane proteins including ion channels2, ion pumps3, and transporters4. Recent developments have combined site-specific fluorophore labeling alongside TEVC to 
concurrently examine the conformational dynamics at specific residues and function of these proteins on the surface of single cells.
We will describe a method to study the conformational dynamics of membrane proteins by simultaneously monitoring fluorescence and current changes using voltage-clamp fluorometry. This approach can be used to examine the molecular motion of membrane proteins site-specifically following cysteine replacement and site-directed fluorophore labeling5,6. Furthermore, this method provides an approach to determine distance constraints between specific residues7,8. 
This is achieved by selectively attaching donor and acceptor fluorophores to two mutated cysteine residues of interest.
In brief, these experiments are performed following functional expression of the desired protein on the surface of Xenopus leavis oocytes. The large surface area of these oocytes enables facile functional measurements and a robust fluorescence signal5. It is also possible to readily change the extracellular conditions such as pH, ligand or cations/anions, which can provide further information on the mechanism of membrane proteins4. Finally, recent developments 
have also enabled the manipulation of select internal ions following co-expression with a second protein9.
Our protocol is described in multiple parts. First, cysteine scanning mutagenesis proceeded by fluorophore labeling is completed at residues located at the interface of the transmembrane and extracellular domains. Subsequent experiments are designed to identify residues which demonstrate large changes in fluorescence intensity (&lt;5%)3 upon a conformational change of the protein. Second, these changes in fluorescence intensity are compared to the kinetic parameters of 
the membrane protein in order to correlate the conformational dynamics to the function of the protein10. This enables a rigorous biophysical analysis of the molecular motion of the target protein. Lastly, two residues of the holoenzyme can be labeled with a donor and acceptor fluorophore in order to determine distance constraints using donor photodestruction methods. It is also possible to monitor the relative movement of protein subunits following labeling with a donor and acceptor fluorophore.

Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling

We will describe a method which measures the kinetics of ion transport of membrane proteins alongside site-specific analysis of conformational changes using fluorescence on single cells. This technique is adaptable to ion channels, transporters and ion pumps and can be utilized to determine distance constraints between protein subunits.

Membran Proteinleri Konformasyonel Dynamics incelenmesi In situ Site Floresan Etiketleme

Two electrode voltage clamp electrophysiology (TEVC) is a powerful tool to investigate the mechanism of ion transport1 for a wide variety of membrane ...

Lineage Labeling of Zebrafish Cells with Laser Uncagable Fluorescein Dextran

A central problem in developmental biology is to deduce the origin of the myriad cell types present in vertebrates as they arise from undifferentiated precursors. Researchers have employed various methods of lineage labeling, such as DiI labeling1 and pressure injection of traceable enzymes2 to ascertain cell fate at later stages of development in model systems. The first fate maps in zebrafish (Danio rerio) were assembled by iontophoretic injection of fluorescent dyes, such as rhodamine dextran, into single cells in discrete regions of the embryo and tracing the labeled cell's fate over time3-5. While effective, these methods are technically demanding and require specialized equipment not commonly found in zebrafish labs. Recently, photoconvertable fluorescent proteins, such as Eos and Kaede, which irreversibly switch from green to red fluorescence when exposed to ultraviolet light, are seeing increased use in zebrafish6-8. The optical clarity of the zebrafish embryo and the relative ease of transgenesis have made these particularily attractive tools for lineage labeling and to observe the migration of cells in vivo7. Despite their utility, these proteins have some disadvantages compared to dye-mediated lineage labeling methods. The most crucial is the difficulty we have found in obtaining high 3-D resolution during photoconversion of these proteins. In this light, perhaps the best combination of resolution and ease of use for lineage labeling in zebrafish makes use of caged fluorescein dextran, a fluorescent dye that is bound to a quenching group that masks its fluorescence9. The dye can then be "uncaged" (released from the quenching group) within a specific cell using UV light from a laser or mercury lamp, allowing visualization of its fluorescence or immunodetection. Unlike iontophoretic methods, caged fluorescein can be injected with standard injection apparatuses and uncaged with an epifluorescence microscope equipped with a pinhole10. In addition, antibodies against fluorescein detect only the uncaged form, and the epitope survives fixation well11. Finally, caged fluorescein can be activated with very high 3-D resolution, especially if two-photon microscopy is employed 12,13. This protocol describes a method of lineage labeling by caged fluorescein and laser uncaging. Subsequenctly, uncaged fluorescein is detected simultaneously with other epitopes such as GFP by labeling with antibodies.

This protocol delineates a way to label and trace the fate of small groups of cells zebrafish embryos using UV-uncaging of caged fluorescein, followed by whole mount immunolabeling to amplify the signal from the uncaged fluorescein.

Lazer Uncagable Floresein Dextran&#39;ın Zebra balığı Hücre Lineage Etiketleme

A central problem in developmental biology is to deduce the origin of the myriad cell types present in vertebrates as they arise from undifferentiated ...

Concentration Determination of Nucleic Acids and Proteins Using the Micro-volume Bio-spec Nano Spectrophotometer

Nucleic Acid quantitation procedures have advanced significantly in the last three decades. More and more, molecular biologists require consistent small-volume analysis of nucleic acid samples for their experiments. The BioSpec-nano provides a potential solution to the problems of inaccurate, non-reproducible results, inherent in current DNA quantitation methods, via specialized optics and a sensitive PDA detector. The BioSpec-nano also has automated functionality such that mounting, measurement, and cleaning are done by the instrument, thereby eliminating tedious, repetitive, and inconsistent placement of the fiber optic element and manual cleaning.
In this study, data is presented on the quantification of DNA and protein, as well as on measurement reproducibility and accuracy. Automated sample contact and rapid scanning allows measurement in three seconds, resulting in excellent throughput. Data analysis is carried out using the built-in features of the software. The formula used for calculating DNA concentration is:
Sample Concentration = DF &middot; (OD260-OD320)&middot; NACF (1)
Where DF = sample dilution factor and NACF = nucleic acid concentration factor.
The Nucleic Acid concentration factor is set in accordance with the analyte selected1.
Protein concentration results can be expressed as &mu;g/ mL or as moles/L by entering e280 and molecular weight values respectively. When residue values for Tyr, Trp and Cysteine (S-S bond) are entered in the e280Calc tab, the extinction coefficient values are calculated as e280 = 5500 x (Trp residues) + 1490 x (Tyr residues) + 125 x (cysteine S-S bond). The e280 value is used by the software for concentration calculation.
In addition to concentration determination of nucleic acids and protein, the BioSpec-nano can be used as an ultra micro-volume spectrophotometer for many other analytes or as a standard spectrophotometer using 5 mm pathlength cells.

This communication presents data on the accuracy and reproducibility of the BioSpec-nano UV-VIS spectrophotometer for dsDNA and protein quantitation. Even with ultra-small volumes (1 to 2 L), reproducibility is excellent, while the automated wiping function improves throughput and results in minimal carryover for more precise results.

Konsantrasyon belirlenmesi Micro hacimli Bio-spec Nano Spektrofotometre Nükleik Asitler ve Proteinler

Nucleic Acid quantitation procedures have advanced significantly in the last three decades.  More and more, molecular biologists require consistent ...

ReAsH/FlAsH Labeling and Image Analysis of Tetracysteine Sensor Proteins in Cells

Fluorescent proteins and dyes are essential tools for the study of protein trafficking, localization and function in cells. While fluorescent 
proteins such as green fluorescence protein (GFP) have been extensively used as fusion partners to proteins to track the properties of a protein of interest1, recent 
developments with smaller tags enable new functionalities of proteins to be examined in cells such as conformational change and protein-association 2, 3. One small 
tag system involves a tetracysteine motif (CCXXCC) genetically inserted into a target protein, which binds to biarsenical dyes, ReAsH (red fluorescent) and FlAsH 
(green fluorescent), with high specificity even in live cells 2. The TC/biarsenical dye system offers far less steric constraints to the host protein than 
fluorescent proteins which has enabled several new approaches to measure conformational change and protein-protein interactions 4-7. We recently developed 
a novel application of TC tags as sensors of oligomerization in cells expressing mutant huntingtin, which when mutated aggregates in neurons in Huntington 
disease 7. Huntingtin was tagged with two fluorescent dyes, one a fluorescent protein to track protein location, and the second a TC tag which only 
binds biarsenical dyes in monomers. Hence, changes in colocalization between protein and biarsenical dye reactivity enabled submicroscopic oligomer 
content to be spatially mapped within cells. Here, we describe how to label TC-tagged proteins fused to a fluorescent protein (Cherry, GFP or CFP) 
with FlAsH or ReAsH in live mammalian cells and how to quantify the two color fluorescence (Cherry/FlAsH, CFP/FlAsH or GFP/ReAsH combinations).

The biarsenical dyes FlAsH and ReAsH bind specifically to tetracysteine motifs in proteins and can selectively label proteins in live cells. Recently this labeling strategy has been used to develop sensors for different protein conformations or oligomeric states. We describe the labeling approach and methods to quantitatively analyze binding.

ReAsH / Flash Etiketleme ve Hücreler Tetracysteine ​​Sensör Proteinlerin Görüntü Analizi

Fluorescent proteins and dyes are essential tools for the study of protein trafficking, localization and function in cells.  While fluorescent 
proteins ...

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine cell central metabolism and discover new enzymes is 13C-assisted metabolism analysis 1. This technique is based on isotopic labeling, whereby microbes are fed with a 13C labeled substrates. By tracing the atom transition paths between metabolites in the biochemical network, we can determine functional pathways and discover new enzymes. 
As a complementary method to transcriptomics and proteomics, approaches for isotopomer-assisted analysis of metabolic pathways contain three major steps 2. First, we grow cells with 13C labeled substrates. In this step, the composition of the medium and the selection of labeled substrates are two key factors. To avoid measurement noises from non-labeled carbon in nutrient supplements, a minimal medium with a sole carbon source is required. Further, the choice of a labeled substrate is based on how effectively it will elucidate the pathway being analyzed. Because novel enzymes often involve different reaction stereochemistry or intermediate products, in general, singly labeled carbon substrates are more informative for detection of novel pathways than uniformly labeled ones for detection of novel pathways3, 4. Second, we analyze amino acid labeling patterns using GC-MS. Amino acids are abundant in protein and thus can be obtained from biomass hydrolysis. Amino acids can be derivatized by N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (TBDMS) before GC separation. TBDMS derivatized amino acids can be fragmented by MS and result in different arrays of fragments. Based on the mass to charge (m/z) ratio of fragmented and unfragmented amino acids, we can deduce the possible labeled patterns of the central metabolites that are precursors of the amino acids. Third, we trace 13C carbon transitions in the proposed pathways and, based on the isotopomer data, confirm whether these pathways are active 2. Measurement of amino acids provides isotopic labeling information about eight crucial precursor metabolites in the central metabolism. These metabolic key nodes can reflect the functions of associated central pathways.
13C-assisted metabolism analysis via proteinogenic amino acids can be widely used for functional characterization of poorly-characterized microbial metabolism1. In this protocol, we will use Cyanothece 51142 as the model strain to demonstrate the use of labeled carbon substrates for discovering new enzymatic functions.

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

13C-isotope labeling is a useful technique for determining the cell central metabolism for various types of microorganisms. After cells have been cultured with a specific labeled substrate, GC-MS measurement can reveal functional metabolic pathways based on unique labeling patterns in proteinogenic amino acids.

Sayesinde Metabolik Pathway Onay ve Keşif 13</supAminoasittir> C-etiketleme

Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine ...

Measuring Cell Cycle Progression Kinetics with Metabolic Labeling and Flow Cytometry

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating cells. Cell cycle division is an integral part of growth and reproduction and deregulation of key cell cycle components have been implicated in the precipitating events of carcinogenesis 1,2. Molecular agents in anti-cancer therapies frequently target biological pathways responsible for the regulation and coordination of cell cycle division 3. Although cell cycle kinetics tend to vary according to cell type, the distribution of cells amongst the four stages of the cell cycle is rather consistent within a particular cell line due to the consistent pattern of mitogen and growth factor expression. Genotoxic events and other cellular stressors can result in a temporary block of cell cycle progression, resulting in arrest or a temporary pause in a particular cell cycle phase to allow for instigation of the appropriate response mechanism. 
The ability to experimentally observe the behavior of a cell population with reference to their cell cycle progression stage is an important advance in cell biology. Common procedures such as mitotic shake off, differential centrifugation or flow cytometry-based sorting are used to isolate cells at specific stages of the cell cycle 4-6. These fractionated, cell cycle phase-enriched populations are then subjected to experimental treatments. Yield, purity and viability of the separated fractions can often be compromised using these physical separation methods. As well, the time lapse between separation of the cell populations and the start of experimental treatment, whereby the fractionated cells can progress from the selected cell cycle stage, can pose significant challenges in the successful implementation and interpretation of these experiments.
Other approaches to study cell cycle stages include the use of chemicals to synchronize cells. Treatment of cells with chemical inhibitors of key metabolic processes for each cell cycle stage are useful in blocking the progression of the cell cycle to the next stage. For example, the ribonucleotide reductase inhibitor hydroxyurea halts cells at the G1/S juncture by limiting the supply of deoxynucleotides, the building blocks of DNA. Other notable chemicals include treatment with aphidicolin, a polymerase alpha inhibitor for G1 arrest, treatment with colchicine and nocodazole, both of which interfere with mitotic spindle formation to halt cells in M phase and finally, treatment with the DNA chain terminator 5-fluorodeoxyridine to initiate S phase arrest 7-9. Treatment with these chemicals is an effective means of synchronizing an entire population of cells at a particular phase. With removal of the chemical, cells rejoin the cell cycle in unison. Treatment of the test agent following release from the cell cycle blocking chemical ensures that the drug response elicited is from a uniform, cell cycle stage-specific population. However, since many of the chemical synchronizers are known genotoxic compounds, teasing apart the participation of various response pathways (to the synchronizers vs. the test agents) is challenging. 
Here we describe a metabolic labeling method for following a subpopulation of actively cycling cells through their progression from the DNA replication phase, through to the division and separation of their daughter cells. Coupled with flow cytometry quantification, this protocol enables for measurement of kinetic progression of the cell cycle in the absence of either mechanically- or chemically- induced cellular stresses commonly associated with other cell cycle synchronization methodologies 10. In the following sections we will discuss the methodology, as well as some of its applications in biomedical research.

Tracking subtle changes in the progression and kinetics of cell cycle stages can be accomplished by use of a combination of metabolic labeling of nucleic acids with BrdU and total genomic DNA staining via Propidium Iodide. This method avoids the need of chemical synchronization of cycling cells, thereby preventing the introduction of non-specific DNA damage, which in turn affects cell cycle progression.

Metabolik Etiketleme ve Flow Sitometri ile Hücre Döngüsü İlerleme Kinetik Ölçüm

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating ...

Analyzing and Building Nucleic Acid Structures with 3DNA

The 3DNA software package is a popular and versatile bioinformatics tool with capabilities to analyze, construct, and visualize three-dimensional nucleic acid structures. This article presents detailed protocols for a subset of new and popular features available in 3DNA, applicable to both individual structures and ensembles of related structures. Protocol 1 lists the set of instructions needed to download and install the software. This is followed, in Protocol 2, by the analysis of a nucleic acid structure, including the assignment of base pairs and the determination of rigid-body parameters that describe the structure and, in Protocol 3, by a description of the reconstruction of an atomic model of a structure from its rigid-body parameters. The most recent version of 3DNA, version 2.1, has new features for the analysis and manipulation of ensembles of structures, such as those deduced from nuclear magnetic resonance (NMR) measurements and molecular dynamic (MD) simulations; these features are presented in Protocols 4 and 5. In addition to the 3DNA stand-alone software package, the w3DNA web server, located at <a href="http://w3dna.rutgers.edu" target="_blank">http://w3dna.rutgers.edu</a>, provides a user-friendly interface to selected features of the software. Protocol 6 demonstrates a novel feature of the site for building models of long DNA molecules decorated with bound proteins at user-specified locations.

The 3DNA software package is a popular and versatile bioinformatics tool with capabilities to analyze, construct, and visualize three-dimensional nucleic acid structures. This article presents detailed protocols for a subset of new and popular features available in 3DNA, applicable to both individual structures and ensembles of related structures.

3DNA ile Nükleik Asit Yapıları analiz ve Yapı

The 3DNA software package is a popular and versatile bioinformatics tool with capabilities to analyze, construct, and visualize three-dimensional nucleic ...