This work was supported by startup funds to TDG from Christopher Newport University.&#160;

1. Preparing the gel
NOTE: For general gel electrophoresis protocols, see also P.Y. Lee, et al.14.&#160;
<ol>
	<li>Mix agarose (~1% w/v, percentage can be varied for particular size separations) in buffer (approximately 70 mL for a mini-gel (8 x&#160;7 cm)). Buffers are commonly TAE (tris-acetate-EDTA, 40 mM Tris, 20 mM acetate, 1 mM EDTA, pH approximately 8.6) or TBE (tris-borate-EDTA, 90 mM Tris, 90 mM borate, 2 mM EDTA, pH approximately 8.3)).</li>
	<li>Add thiazole orange to a final concentration of 1.3 &#956;g/mL.
	<ol>
		<li>Dissolve thiazole orange in DMSO to make a 10,000x stock solution (13 mg/mL). While not particularly light sensitive, store TO in the dark when not in use. This solution is stable at room temperature for ~months; long-term storage may be achieved by freezing aliquots (DMSO will freeze in a standard refrigerator). Be sure to entirely melt and resuspend a frozen solution before use.&#160; 
		NOTE: The gel can also be stained with TO after electrophoresis (see step 2.6). While TO has an improved safety profile over ethidium bromide, standard molecular biology laboratory safety precautions should be maintained.&#160;</li>
	</ol>
	</li>
	<li>Microwave the mixture of agarose, buffer, and thiazole orange to dissolve agarose (approximately 60 s). This step is commonly referred to as &#8220;melting&#8221;. Swirl (5 s) to aid dissolution if needed.&#160; 
	NOTE: TO can also be added after microwaving if preferred.</li>
	<li>Allow the agarose solution to cool briefly before pouring into gel casting apparatus containing an appropriate comb.</li>
	<li>Allow the agarose solution to solidify into a gel.&#160;</li>
</ol>
2. Loading and running the gel
<ol>
	<li>Place the gel in the electrophoresis apparatus if not already present.</li>
	<li>Add running buffer (TAE or TBE as above) to cover the surface of the gel.</li>
	<li>Load DNA samples (commonly 10 &#956;L) using a loading dye. Include a DNA sizing ladder for reference.</li>
	<li>Attach the cover and electrodes (the gel should be run toward the red anode (positive)).</li>
	<li>Apply voltage (typically ~100V for a mini-gel, although size of gel may require a modified voltage to prevent damaging the gel) until loading dye has traveled an appropriate distance (approximately 4-7 cm for a mini-gel, although distance may vary depending on precise application). 
	NOTE: Like ethidium bromide and many other DNA-binding dyes, thiazole orange is positively charged. Consequently, these dyes will migrate in the opposite direction of electrophoresing DNA. For samples which are run far down the gel for enhanced separation, eventually the dye will separate from the smaller DNA fragments, resulting in weak staining. In these instances, the gel should be stained as in step 2.6. This situation is not unique to TO, any positively charged dye that reversibly interacts with DNA will exhibit this behavior (including ethidium bromide, TO, and others).</li>
	<li>If TO was not added prior to gel casting (step 1.2), stain by immersing the gel in the buffer containing thiazole orange.
	<ol>
		<li>Prepare enough buffer (TAE or TBE) containing 1.3 &#956;g/mL thiazole orange to completely cover the gel and soak the gel with gentle agitation until the bands are fully detected (roughly 20 min).</li>
	</ol>
	</li>
</ol>
3. Visualization of thiazole orange agarose gel (UV transilluminator)
<ol>
	<li>Remove the gel from the electrophoresis apparatus and place on a UV transilluminator. 
	CAUTION: UV light is damaging to skin and eyes. Be sure to wear appropriate eye (goggles) and face (face shield) protection. Hands should have gloves and long sleeves should be worn.</li>
	<li>If desired, cut out desired DNA bands from the gel (for further digestion or ligation, for example). Expose the gel to UV light for as short a length of time as possible during excision. UV light (regardless of DNA dye) damages DNA.&#160;</li>
	<li>Extract DNA from the gel slice using a readily available kit or protocol15.</li>
</ol>
4. Visualization of thiazole orange agarose gel (blue-light transilluminator or flashlight)
<ol>
	<li>Remove the gel from the electrophoresis apparatus and place on a blue-light transilluminator (~470 nm maximum emission wavelength). Alternatively, a blue LED (~470 nm) flashlight can be directed at the gel (either from above or below). 
	NOTE: While sensitivity is lower using a blue-light transilluminator with ethidium bromide, DNA stained with ethidium bromide can be detected using this blue-light protocol.</li>
	<li>Use an amber emission filter (~560 nm longpass, either goggles or square) to filter blue light, enabling visualization of fluorescence from DNA:thiazole orange complexes.&#160; 
	NOTE: Without the amber emission filter, it is very difficult to detect DNA bands due to intensity of blue-light excitation source.&#160; 
	CAUTION: Although blue light lacks the ability to acutely damage tissues (contrasting UV), prolonged exposure to intense blue light could damage eyes and amber emission goggles or filter should be used.</li>
	<li>If desired, cut out desired DNA bands from the gel for further applications. 
	NOTE: Since blue light does not damage DNA, it is not necessary to rapidly cut out bands (such as when using UV excitation in step 3.2).</li>
	<li>Extract DNA from the gel slice using a readily available kit or protocol15.</li>
</ol>
5. Image capture
<ol>
	<li>Select appropriate excitation and emission settings in gel-imaging apparatus. The excitation and emission of thiazole orange (&#955;ex,max = 510 nm (488 nm and 470 nm also show strong excitation, in addition to strong excitation at UV wavelengths); &#955;em = 527 nm) are nearly identical to common blue-light&#8211;detectable commercial dyes, so instruments may have preset filter settings that can be used.&#160; 
	NOTE: Some filter settings for blue-light&#8211;detectable commercial dyes actually use damaging UV light for excitation, so use caution if imaging prior to cutting out bands. Use a blue-light excitation source if possible when DNA bands will be excised after imaging.</li>
	<li>In the absence of an imaging system with appropriate filters, place an amber filter between the camera and the gel/blue-light excitation source.</li>
</ol>

<ol>
	<li>O'Neil, C. S., Beach, J. L., Gruber, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thiazole+orange+as+an+everyday+replacement+for+ethidium+bromide+and+costly+DNA+dyes+for+electrophoresis.">Thiazole orange as an everyday replacement for ethidium bromide and costly DNA dyes for electrophoresis.</a> Electrophoresis. 39 (12), 1474-1477 (2018).</li><li>McCann, J., Choi, E., Yamasaki, E., Ames, B. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+carcinogens+as+mutagens+in+the+Salmonella/microsome+test:+assay+of+300+chemicals.">Detection of carcinogens as mutagens in the Salmonella/microsome test: assay of 300 chemicals.</a> Proceedings of the National Academy of Sciences of the United States of America. 72 (12), 5135-5139 (1975).</li><li>Evenson, W. E., Boden, L. M., Muzikar, K. A., O&#8217;Leary, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=1H+and+13C+NMR+Assignments+for+the+Cyanine+Dyes+SYBR+Safe+and+Thiazole+Orange.">1H and 13C NMR Assignments for the Cyanine Dyes SYBR Safe and Thiazole Orange.</a> The Journal of Organic Chemistry. 77 (23), 10967-10971 (2012).</li><li>Beaudet, M., Cox, G., Yue, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular Probes, Inc. , (2005).</li><li>Pfeifer, G. P., You, Y. H., Besaratinia, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutations+induced+by+ultraviolet+light.">Mutations induced by ultraviolet light.</a> Mutation Research. 571 (1-2), 19-31 (2005).</li><li>Cariello, N. F., Keohavong, P., Sanderson, B. J., Thilly, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+damage+produced+by+ethidium+bromide+staining+and+exposure+to+ultraviolet+light.">DNA damage produced by ethidium bromide staining and exposure to ultraviolet light.</a> Nucleic Acids Research. 16 (9), 4157 (1988).</li><li>Hartman, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transillumination+can+profoundly+reduce+transformation+frequencies.">Transillumination can profoundly reduce transformation frequencies.</a> BioTechniques. 11 (6), 747-748 (1991).</li><li>Lee, L. G., Chen, C. H., Chiu, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thiazole+orange:+a+new+dye+for+reticulocyte+analysis.">Thiazole orange: a new dye for reticulocyte analysis.</a> Cytometry. 7 (6), 508-517 (1986).</li><li>Nygren, J., Svanvik, N., Kubista, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Interactions+Between+the+Fluorescent+Dye+Thiazole+Orange+and+DNA.">The Interactions Between the Fluorescent Dye Thiazole Orange and DNA.</a> Biopolymers. , 1-13 (1998).</li><li>Svanvik, N., Westman, G., Wang, D., Kubista, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-Up+Probes:+Thiazole+Orange-Conjugated+Peptide+Nucleic+Acid+for+Detection+of+Target+Nucleic+Acid+in+Homogeneous+Solution.">Light-Up Probes: Thiazole Orange-Conjugated Peptide Nucleic Acid for Detection of Target Nucleic Acid in Homogeneous Solution.</a> Analytical Biochemistry. 281 (1), 26-35 (2000).</li><li>Yang, P., De Cian, A., Teulade-Fichou, M. P., Mergny, J. L., Monchaud, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+Bisquinolinium/Thiazole+Orange+Conjugates+for+Fluorescent+Sensing+of+G-Quadruplex+DNA.">Engineering Bisquinolinium/Thiazole Orange Conjugates for Fluorescent Sensing of G-Quadruplex DNA.</a> Angewandte Chemie International Edition. 48 (12), 2188-2191 (2009).</li><li>Fang, G. M., Chamiolo, J., Kankowski, S., Hovelmann, F., Friedrich, D., Lower, A., Meier, J. C., Seitz, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+bright+FIT-PNA+hybridization+probe+for+the+hybridization+state+specific+analysis+of+a+C+&#8594;+U+RNA+edit+via+FRET+in+a+binary+system.">A bright FIT-PNA hybridization probe for the hybridization state specific analysis of a C &#8594; U RNA edit via FRET in a binary system.</a> Chemical Science. 9 (21), 4794-4800 (2018).</li><li>Pei, R., Rothman, J., Xie, Y., Stojanovic, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-up+properties+of+complexes+between+thiazole+orange-small+molecule+conjugates+and+aptamers.">Light-up properties of complexes between thiazole orange-small molecule conjugates and aptamers.</a> Nucleic Acids Research. 37 (8), e59-e59 (2009).</li><li>Lee, P. Y., Costumbrado, J., Hsu, C. Y., Kim, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agarose+Gel+Electrophoresis+for+the+Separation+of+DNA+Fragments.">Agarose Gel Electrophoresis for the Separation of DNA Fragments.</a> Journal of Visualized Experiments. (62), 1-5 (2012).</li><li>Vogelstein, B., Gillespie, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparative+and+analytical+purification+of+DNA+from+agarose.">Preparative and analytical purification of DNA from agarose.</a> Proceedings of the National Academy of Sciences of the United States of America. 76 (2), 615-619 (1979).</li></ol>

The authors have nothing to disclose.

Ethidium bromide has long been a standard tool in the molecular biology lab, despite known toxicity. It also suffers from requiring UV light, which damages the DNA as it is being detected. Thiazole orange offers an inexpensive alternative to ethidium bromide, as well as useful but expensive commercial dyes.&#160;
The benefits of thiazole orange are thus two-fold. First, thiazole orange can simply be used as a replacement to ethidium bromide. Gels can be prepared identically to EtBr, with TO su...

The purpose of this method is to identify DNA in agarose gels using thiazole orange (TO) for fluorescence detection. Due to its low cost and favorable safety profile, thiazole orange may see particular benefit in undergraduate teaching labs and research labs performing molecular biology, especially ligations and cloning.
Ethidium bromide remains the most common dye for detection of DNA in agarose gels. This is primarily because it can be obtained very inexpensively and only requires excitation with UV light for detection. Both ethidium bromide and thiazole orange are inexpensive, with low detection limits (1-2 ng/lane)1. There are two main drawbacks to ethidium bromide, however, that thiazole orange improves upon.&#160;
First, ethidium bromide is a mutagen2 with special handling, shipping, and disposal requirements, whereas thiazole orange is less mutagenic (3&#8211;4x less mutagenic in Ames test)3,4 and can be generally disposed of with common chemical waste.
Second, ethidium bromide requires UV light for detection. Thiazole orange can similarly use UV light if desired, but can also be detected with blue light. UV light, while commonly used, has a few salient disadvantages. First, it is damaging to human skin and eyes. While UV light can be used safely by trained professionals, accidental skin or eye damage (functionally similar to sunburns) from laboratory UV light are not uncommon particularly with inexperienced scientists. Second, UV light is extremely damaging to DNA samples5, which reduces the success of downstream experiments (such as ligation and transformation)1,6,7. TO allows detection with blue light (&#955;ex,max = 510 nm (488 nm and 470 nm also show strong excitation)), which does not cause skin damage or DNA damage (although any intense light may still be harmful to eyes), greatly decreasing the risks to both the scientist and the sample.&#160;
TO is not the only fluorescent dye alternative to ethidium bromide; its advantage is cost. TO was discovered in the 1980s as a reticulocyte stain8, and has found utility in a number of DNA-based fluorescence experiments9,10,11,12,13. It is currently sold by multiple suppliers. TO is the parent compound of additional, more expensive, blue-light&#8211;detectable commercial dyes, and behaves similarly during electrophoresis, using UV or blue light for detection1. Furthermore, while other dyes are more sensitive to very low DNA concentrations than either EtBr or TO, for generic electrophoresis experiments, such dyes are prohibitively expensive in many contexts.&#160;

<table border="0" cellpadding="0" cellspacing="0" style="width:572px;" width="573">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">2-log DNA ladder</td>
			<td style="width:71px;">New England Biolabs</td>
			<td style="width:119px;">N0469S</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Agarose (Genetic Analysis Grade)</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">BP1356-100</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Blue-light flashlight</td>
			<td style="width:71px;">WAYLLSHINE (Amazon)</td>
			<td style="width:119px;">WAYLLSHINE Scalable Blue LED</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ChemiDoc MP</td>
			<td style="width:71px;">Biorad</td>
			<td style="width:119px;">1708280</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">DMSO</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">D8418</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ethidium bromide</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">BP1302-10</td>
			<td>For comparison, not necessary for protocol</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Gel apparatus (Owl Easy Cast)</td>
			<td style="width:71px;">Thermo Scientific</td>
			<td style="width:119px;">B1A</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Qiagen Qiaquick Gel extraction kit</td>
			<td style="width:71px;">Qiagen</td>
			<td style="width:119px;">28704</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Safe Imager Viewing Glasses</td>
			<td style="width:71px;">Invitrogen</td>
			<td style="width:119px;">S37103</td>
			<td>Necessary for using blue light flashlight.*</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">SafeImager 2.0 (Blue light transilluminator)</td>
			<td style="width:71px;">Invitrogen</td>
			<td style="width:119px;">G6600</td>
			<td>Blue light flashlight may be used as alternative</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">SYBR Safe</td>
			<td style="width:71px;">Invitrogen</td>
			<td style="width:119px;">S33102</td>
			<td>For comparison, not necessary for protocol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TAE (Tris-Acetate-EDTA)</td>
			<td style="width:71px;">Corning</td>
			<td style="width:119px;">46-010-CM</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Thiazole orange</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">390062</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>*Glasses are also included with Invitrogen G6600</td>
		</tr>
	</tbody>
</table>

dna electrophoresis using thiazole orange instead of ethidium bromide or alternative dyes

DNA gel electrophoresis using agarose is a common tool in molecular biology laboratories, allowing separation of DNA fragments by size. After separation, DNA is visualized by staining. This article demonstrates how to use thiazole orange to stain DNA. Thiazole orange compares favorably to common staining methods, in that it is sensitive, inexpensive, excitable with UV or blue light (to prevent sample damage), and safer than ethidium bromide. Labs already equipped to run DNA electrophoresis experiments using ethidium bromide can generally switch dyes with no additional changes to existing protocols, using UV light for detection. Blue-light detection to avoid sample damage can additionally be achieved with a blue-light source and emission filter. Labs already equipped for blue-light detection can simply switch dyes with no additional changes to existing protocols.

Thiazole orange enables detection of DNA, without using ethidium bromide and without using DNA-damaging UV light. Ethidium bromide is well-known to be mutagenic, so eliminating it from the lab may be advantageous. UV light damages DNA and lowers transformation efficiency significantly, whereas blue light does not damage DNA. Detection limits are similar between ethidium bromide, thiazole orange, and a common, blue-light&#8211;detectable commercial DNA dye (Figure 1, see Table of Mate...

Watch this Scientific Journal Video about DNA Electrophoresis Using Thiazole Orange Instead of Ethidium Bromide or Alternative Dyes at JoVE.com

DNA Electrophoresis Using Thiazole Orange Instead of Ethidium Bromide or Alternative Dyes

Here, we present a protocol to use thiazole orange for the detection of DNA in gel electrophoresis experiments. The use of thiazole orange allows elimination of ethidium bromide, and fluorescence detection can be achieved with either UV or blue light.

DNA gel electrophoresis using agarose is a common tool in molecular biology laboratories, allowing separation of DNA fragments by size. After separation, ...

dna-electrophoresis-using-thiazole-orange-instead-ethidium-bromide-or

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Biochemistry

13.7K Views.  Christopher Newport University. Here, we present a protocol to use thiazole orange for the detection of DNA in gel electrophoresis experiments. The use of thiazole orange allows elimination of ethidium bromide, and fluorescence detection can be achieved with either UV or blue light.

Video: DNA Electrophoresis Using Thiazole Orange Instead of Ethidium Bromide or Alternative Dyes

Characterization of Multi-subunit Protein Complexes of Human MxA Using Non-denaturing Polyacrylamide Gel-electrophoresis

The formation of oligomeric complexes is a crucial prerequisite for the proper structure and function of many proteins. The interferon-induced antiviral effector protein MxA exerts a broad antiviral activity against many viruses. MxA is a dynamin-like GTPase and has the capacity to form oligomeric structures of higher order. However, whether oligomerization of MxA is required for its antiviral activity is an issue of debate. We describe here a simple protocol to assess the oligomeric state of endogenously or ectopically expressed MxA in the cytoplasmic fraction of human cell lines by non-denaturing polyacrylamide gel electrophoresis (PAGE) in combination with Western blot analysis. A critical step of the protocol is the choice of detergents to prevent aggregation and/or precipitation of proteins particularly associated with cellular membranes such as MxA, without interfering with its enzymatic activity. Another crucial aspect of the protocol is the irreversible protection of the free thiol groups of cysteine residues by iodoacetamide to prevent artificial interactions of the protein. This protocol is suitable for a simple assessment of the oligomeric state of MxA and furthermore allows a direct correlation of the antiviral activity of MxA interface mutants with their respective oligomeric states.

This article describes a simple and rapid protocol to evaluate the oligomeric state of the dynamin-like GTPase MxA protein from lysates of human cells using a combination of non-denaturing PAGE with western blot analysis.

The formation of oligomeric complexes is a crucial prerequisite for the proper structure and function of many proteins. The interferon-induced antiviral ...

Capillary Electrophoresis Separation of Monoclonal Antibody Isoforms Using a Neutral Capillary

Biotherapeutic proteins, such as monoclonal antibodies (mAbs), are feasible alternatives for the treatment of chronic-degenerative diseases. The biological activity of these proteins depends on their physicochemical properties. The use of high-performance techniques like chromatography and capillary electrophoresis has been described for the analysis of physicochemical heterogeneity of mAbs. Nowadays, capillary zone electrophoresis (CZE) technique constitutes one of the most resolutive and sensitive assays for the analysis of biomolecules. Besides, the electro-driven separation in CZE is governed by extensive properties of matter and offers the advantage of analyzing proteins close to their native state. However, the successful implementation of this technique for routine analysis depends on the skills of the analyst at the critical steps during sample and system preparation. The purpose of this tutorial is to detail the steps to succeed in the CZE analysis of mAbs. Further, this protocol can be used for the development and improvement of skills of the personnel involved in protein analytical chemistry laboratories.

Here, we present a comprehensive capillary zone electrophoresis protocol for the assessment of intrinsic physicochemical heterogeneity of monoclonal antibodies as a quality attribute.

Biotherapeutic proteins, such as monoclonal antibodies (mAbs), are feasible alternatives for the treatment of chronic-degenerative diseases. The ...

Horizontal Gel Electrophoresis for Enhanced Detection of Protein-RNA Complexes

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of RNA-protein interactions. These interactions have been traditionally analyzed with polyacrylamide gels generated between two glass plates and samples electrophoresed vertically. However, polyacrylamide gels cast in trays and electrophoresed horizontally offers several advantages. For example, horizontal gels used to analyze complexes between fluorescent RNA substrates and specific proteins can be imaged multiple times as electrophoresis progresses. This provides the unique opportunity to monitor RNA-protein complexes at several points during the experiment. In addition, horizontal gel electrophoresis makes it possible to analyze many samples in parallel. This can greatly facilitate time course experiments as well as analyzing multiple reactions simultaneously to compare different components and conditions. Here we provide a detailed protocol for generating and using horizontal native gel electrophoresis for analyzing RNA-Protein interactions.

Native polyacrylamide gel electrophoresis is a fundamental tool for analyzing RNA-protein interactions. Traditionally most experiments have used vertical gels. However, horizontal gels provide several advantages, such as the opportunity to monitor complexes during electrophoresis. We provide a detailed protocol for generating and using horizontal native gel electrophoresis.

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of ...

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis can be characterized using an in vitro DNA synthesis assay followed by polyacrylamide gel electrophoresis. The goal of this assay is to quantify synthesis of both natural DNA and modified DNA (M-DNA). These approaches are particularly useful for resolving oligonucleotides with single nucleotide resolution, enabling observation of individual steps during enzymatic oligonucleotide synthesis. These methods have been applied to the evaluation of an array of biochemical and biophysical properties such as the measurement of steady-state rate constants of individual steps of DNA synthesis, the error rate of DNA synthesis, and DNA binding affinity. By using modified components including, but not limited to, modified nucleoside triphosphates (NTP), M-DNA, and/or mutant DNA polymerases, the relative utility of substrate-DNA polymerase pairs can be effectively evaluated. Here, we detail the assay itself, including the changes that must be made to accommodate nontraditional primer DNA labeling strategies such as near-infrared fluorescently labeled DNA. Additionally, we have detailed crucial technical steps for acrylamide gel pouring and running, which can often be technically challenging.

This protocol describes the characterization of DNA polymerase synthesis of modified DNA through observation of changes to near-infrared fluorescently labeled DNA using gel electrophoresis and gel imaging. Acrylamide gels are used for high resolution imaging of the separation of short nucleic acids, which migrate at different rates depending on size.

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis ...

An Alternative Culture Method to Maintain Genomic Hypomethylation of Mouse Embryonic Stem Cells Using MEK Inhibitor PD0325901 and Vitamin C

Embryonic stem (ES) cells have the potential to differentiate into any of the three germ layers (endoderm, mesoderm, or ectoderm), and can generate many lineages for regenerative medicine. ES cell culture in vitro has long been the subject of widespread concerns. Classically, mouse ES cells are maintained in serum and leukemia inhibitory factor (LIF)-containing medium. However, under serum/LIF conditions, cells show heterogeneity in morphology and the expression profile of pluripotency-related genes, and are mostly in a metastable state. Moreover, cultured ES cells exhibit global hypermethylation, but na&#239;ve ES cells of the inner cell mass (ICM) and primordial germ cells (PGCs) are in a state of global hypomethylation. The hypomethylated state of ICM and PGCs is closely associated with their pluripotency. To improve mouse ES cell culture methods, we have recently developed a new method based on the selectively combined utilization of two small-molecule compounds to maintain the DNA hypomethylated and pluripotent state. Here, we present that the co-treatment of vitamin C (Vc) and PD0325901 can erase about 90% of 5-methylcytosine (5mC) at 5 days in mouse ES cells. The generated 5mC content is comparable to that in PGCs. The mechanistic investigation shows that PD0325901 up-regulates Prdm14 expression to suppress Dnmt3b (de novo DNA methyltransferase) and Dnmt3l (the cofactor of Dnmt3b), by reducing de novo 5mC synthesis. Vc facilitates the conversion of 5mC to 5-hydroxymethylcytosine (5hmC) catalyzed mainly by Tet1 and Tet2, indicating the involvement of both passive and active DNA demethylations. Moreover, under Vc/PD0325901 conditions, mouse ES cells show homogeneous morphology and pluripotent state. Collectively, we propose a novel and chemical-synergy culture method for achieving DNA hypomethylation and maintenance of pluripotency in mouse ES cells. The small-molecule chemical-dependent method overcomes the major shortcomings of serum culture, and holds promise to generate homogeneous ES cells for further clinical applications and researches.

We described in detail two chemical-based protocols for culturing mouse embryonic stem cells. This new method utilizes synergistic mechanisms of promoting Tet-mediated oxidation (by vitamin C) and repressing de novo synthesis of 5-methylcytosine (by PD0325901) to maintain DNA hypomethylation and pluripotency of mouse embryonic stem cells.

Embryonic stem (ES) cells have the potential to differentiate into any of the three germ layers (endoderm, mesoderm, or ectoderm), and can generate many ...

Use of Two Dimensional Semi-denaturing Detergent Agarose Gel Electrophoresis to Confirm Size Heterogeneity of Amyloid or Amyloid-like Fibers

Amyloid or amyloid-like fibers have been associated with many human diseases, and are now being discovered to be important for many signaling pathways. The ability to readily detect the formation of these fibers under various experimental conditions is essential for understanding their potential function. Many methods have been used to detect the fibers, but not without some drawbacks. For example, electron microscopy (EM), or staining with Congo Red or Thioflavin T often requires purification of the fibers. On the other hand, semi-denaturing detergent agarose gel electrophoresis (SDD-AGE) allows detection of the SDS-resistant amyloid-like fibers in the cell extracts without purification. In addition, it allows the comparison of the size difference of the fibers. More importantly, it can be used to identify specific proteins within the fibers by Western blotting. It is less time consuming and more easily accessible to a wider number of labs. SDD-AGE results often show variable degree of heterogeneity. It raises the question whether part of the heterogeneity results from the dissociation of the protein complex during the electrophoresis in the presence of SDS. For this reason, we have employed a second dimension of SDD-AGE to determine if the size heterogeneity seen in SDD-AGE is truly a result of fiber heterogeneity in vivo and not a result of either degradation or dissociation of some of the proteins during electrophoresis. This method allows fast, qualitative confirmation that the amyloid or amyloid-like fibers are not partially dissociating during the SDD-AGE process.

Here we use two-dimensional semi-denaturing agarose gel electrophoresis to confirm the presence of amyloid-like fibers of heterogeneous size and exclude the possibility that the size heterogeneity is due to dissociation of the amyloid fibers during the gel running process.

Amyloid or amyloid-like fibers have been associated with many human diseases, and are now being discovered to be important for many signaling pathways. ...

Analysis of AtHIRD11 Intrinsic Disorder and Binding Towards Metal Ions by Capillary Gel Electrophoresis and Affinity Capillary Electrophoresis

Plants are strongly dependent on their environment. In order to adjust to stressful changes (e.g., drought and high salinity), higher plants evolve classes of intrinsically disordered proteins (IDPs) to reduce oxidative and osmotic stress. This article uses a combination of capillary gel electrophoresis (CGE) and mobility shift affinity electrophoresis (ACE) in order to describe the binding behavior of different conformers of the IDP AtHIRD11 from Arabidopsis thaliana. CGE is used to confirm the purity of AtHIRD11 and to exclude fragments, posttranslational modifications, and other impurities as reasons for complex peak patterns. In this part of the experiment, the different sample components are separated by a viscous gel inside a capillary by their different masses and detected with a diode array detector. Afterward, the binding behavior of the sample towards various metal ions is investigated by ACE. In this case, the ligand is added to the buffer solution and the shift in migration time is measured in order to determine whether a binding event has occurred or not. One of the advantages of using the combination of CGE and ACE to determine the binding behavior of an IDP is the possibility to automate the gel electrophoresis and the binding assay. Furthermore, CGE shows a lower limit of detection than the classical gel electrophoresis and ACE is able to determine the manner of binding a ligand in a fast manner. In addition, ACE can also be applied to other charged species than metal ions. However, the use of this method for binding experiments is limited in its ability to determine the number of binding sites. Nevertheless, the combination of CGE and ACE can be adapted for characterizing the binding behavior of any protein sample towards numerous charged ligands.

This protocol combines the characterization of a protein sample by capillary gel electrophoresis and a fast-binding screening for charged ligands by affinity capillary electrophoresis. It is recommended for proteins with a flexible structure, such as intrinsically disordered proteins, to determine any differences in binding for different conformers.

Plants are strongly dependent on their environment. In order to adjust to stressful changes (e.g., drought and high salinity), higher plants evolve ...

DNA Sequence Recognition by DNA Primase Using High-Throughput Primase Profiling

DNA primase synthesizes short RNA primers that initiate DNA synthesis of Okazaki fragments on the lagging strand by DNA polymerase during DNA replication. The binding of prokaryotic DnaG-like primases to DNA occurs at a specific trinucleotide recognition sequence. It is a pivotal step in the formation of Okazaki fragments. Conventional biochemical tools that are used to determine the DNA recognition sequence of DNA primase provide only limited information. Using a high-throughput microarray-based binding assay and consecutive biochemical analyses, it has been shown that 1) the specific binding context (flanking sequences of the recognition site) influences the binding strength of the DNA primase to its template DNA, and 2) stronger binding of primase to the DNA yields longer RNA primers, indicating higher processivity of the enzyme. This method combines PBM and primase activity assay and is designated as high-throughput primase profiling (HTPP), and it allows characterization of specific sequence recognition by DNA primase in unprecedented time and scalability.&#160;

Protein binding microarray (PBM) experiments combined with biochemical assays link the binding and catalytic properties of DNA primase, an enzyme that synthesizes RNA primers on template DNA. This method, designated as high-throughput primase profiling (HTPP), can be used to reveal DNA-binding patterns of a variety of enzymes.

DNA primase synthesizes short RNA primers that initiate DNA synthesis of Okazaki fragments on the lagging strand by DNA polymerase during DNA replication. ...

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Inositol phosphates and phosphoinositides regulate several cellular processes in eukaryotes, including gene expression, vesicle trafficking, signal transduction, metabolism, and development. These metabolites perform this regulatory activity by binding to proteins, thereby changing protein conformation, catalytic activity, and/or interactions. The method described here uses affinity chromatography coupled to mass spectrometry or Western blotting to identify proteins that interact with inositol phosphates or phosphoinositides. Inositol phosphates or phosphoinositides are chemically tagged with biotin, which is then captured via streptavidin conjugated to agarose or magnetic beads. Proteins are isolated by their affinity of binding to the metabolite, then eluted and identified by mass spectrometry or Western blotting. The method has a simple workflow that is sensitive, non-radioactive, liposome-free, and customizable, supporting the analysis of protein and metabolite interaction with precision. This approach can be used in label-free or in amino acid-labelled quantitative mass spectrometry methods to identify protein-metabolite interactions in complex biological samples or using purified proteins. This protocol is optimized for the analysis of proteins from Trypanosoma brucei, but it can be adapted to related protozoan parasites, yeast or mammalian cells.

This protocol focuses on the identification of proteins that bind to inositol phosphates or phosphoinositides. It uses affinity chromatography with biotinylated inositol phosphates or phosphoinositides that are immobilized via streptavidin to agarose or magnetic beads. Inositol phosphate or phosphoinositide binding proteins are identified by Western blotting or mass spectrometry.

Inositol phosphates and phosphoinositides regulate several cellular processes in eukaryotes, including gene expression, vesicle trafficking, signal ...

Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry

Inositol pyrophosphates (PP-InsPs) are an important group of intracellular signaling molecules. Derived from inositol phosphates (InsPs), these molecules feature the presence of at least one energetic pyrophosphate moiety on the myo-inositol ring. They exist ubiquitously in eukaryotes and operate as metabolic messengers surveying phosphate homeostasis, insulin sensitivity, and cellular energy charge. Owing to the absence of a chromophore in these metabolites, a very high charge density, and low abundance, their analysis requires radioactive tracer, and thus it is convoluted and expensive. Here, the study presents a detailed protocol to perform absolute and high throughput quantitation of inositol pyrophosphates from mammalian cells by capillary electrophoresis electrospray ionization mass spectrometry (CE-ESI-MS). This method enables the sensitive profiling of all biologically relevant PP-InsPs species in mammalian cells, enabling baseline separation of regioisomers. Absolute cellular concentrations of PP-InsPs, including minor isomers, and monitoring of their temporal changes in HCT116 cells under several experimental conditions are presented.

A procedure for capillary electrophoresis electrospray ionization mass spectrometry for the absolute quantitation of inositol pyrophosphates from mammalian cell extracts is described.

Inositol pyrophosphates (PP-InsPs) are an important group of intracellular signaling molecules. Derived from inositol phosphates (InsPs), these molecules ...