S.E anerkennt die Unterstützung von Duke Stiftungsfonds besondere Initiative, Wells Fargo Fonds, PhRMA Stiftung sowie Startup-Fonds von der University of North Carolina, Charlotte.

(1) Synthese von BSA-Au(III) Komplex
<ol><li>25 mg der BSA in 1 mL Hochleistungs-Flüssigkeitschromatographie (HPLC) Grade Wasser in einer 5 mL Reaktion Phiole zu lösen. Hinweis: Die Lösung sollte klar angezeigt werden.</li>
	<li>Gold (III) chlorid Trihydrate (chlorogoldsäure) zu einer Konzentration von 5 mM in HPLC Grade Wasser auflösen. Hinweis: Die Lösung sollte gelb angezeigt. Chloroauric Säure Lösung vorbereitet bei dieser Konzentration führt zu einem BSA in Au Verhältnis von 01:13.<ol>
<li>Alternativ bereiten Sie eine Lösung von chlorogoldsäure mit einer Konzentration von überall zwischen 0,38 mM (BSA:Au = 1:1) bis 20 mM (BSA:Au = 01:50) in HPLC Grad Wasser. Hinweis: Unterschiedliche Verhältnisse der BSA Gold drastisch unterschiedlich rote Fluoreszenz-Muster der Erregung-Emission Karte führt.</li>
	</ol>
</li>
	<li>Die Reaktion Phiole der BSA in einem 37 ° C Wasserbad legen und kräftig rühren bei 750 u/min mit einem Magnetrührer.</li>
	<li>Unmittelbar nach der Aufregung beginnt, fügen Sie 1 mL der chlorogoldsäure der Projektmappe hinzu. Die Farbe der Lösung sollte von klar bis gelb verwandeln.</li>
	<li>Rühren Sie die Mischung für 2 min bei 37 ° C und bei 750 u/min mit einem Magnetrührer.</li>
	<li>Fügen Sie in das Fläschchen Reaktion 100 μL 1 M NaOH Lösung bringen den pH-Wert auf 12 hinzu. Hinweis: Unmittelbar nach NaOH hinzugefügt wird, die Lösung sollte leicht zu einem gelb-braun zu verdunkeln und dann zurückdrehen bis gelb.</li>
	<li>Weiterhin rühren bei 750 u/min für 2 h und bei 37 ° C. Die Lösung sollte langsam von Gelb in eine dunkle gelb/braun Farbe ändern. Diese Farbveränderung zeigt die Bildung der roten fluoreszierenden BSA-Au(III) komplexe.</li>
	<li>Lassen Sie die Probe bei Raumtemperatur für 2 Tage und die Lösung zu sitzen wird weiterhin ein Bernstein Braun verdunkeln und die Fluoreszenzintensität erhöht.<ol>
<li>Alternativ lassen Sie die Probe bei 37 ° C für 12 rühren mehr h wie die Farbe der Lösung zu einem braunen Bernstein entwickelt sich weiter.</li>
	</ol>
</li>
</ol>(2) Synthese von BSA-Cu(II)-Au(III)
<ol><li>25 mg der BSA in 1 mL HPLC Grade Wasser auflösen. Die Lösung sollte klar erscheinen.</li>
	<li>Kupfer (II)-chlorid-Dihydrat in HPLC Grade Wasser zu einer Konzentration von 5 mM zu lösen. Die Lösung sollte Licht erscheinen blau.</li>
	<li>Eine Reaktion Ampulle 5 mL 1 mL der wässrigen BSA-Lösung hinzu und legen Sie in einem Wasserbad bei 37 ° C. Rühren Sie die Mischung bei 750 u/min.</li>
	<li>Sofort die Reaktion Phiole 0,5 mL Kupfer (II)-chlorid-Dihydrat-Lösung hinzu und mischen Sie 2 min. lang. Die Lösung bleibt Licht blau.</li>
	<li>Fügen Sie 75 μL 1 M NaOH bis pH 12 und 2 h zu mischen. Die Lösung wird lila werden.</li>
	<li>Lösen Sie chlorogoldsäure in HPLC Grade Wasser zu einer Konzentration von 5 mM auf.</li>
	<li>Die Reaktion Phiole 0,5 mL wässrige chlorogoldsäure hinzu und passen Sie den pH-Wert wieder auf 12 mit 1 M NaOH.</li>
	<li>Rühren Sie das Reaktionsgemisch für 2 h. Hinweis: Die Lösung sollte auf eine braune Farbe zu entwickeln.</li>
</ol>(3) Synthese von BSA-Ni(II)-Au(III)
<ol><li>25 mg der BSA in 1 mL HPLC Grade Wasser auflösen. Die Lösung sollte klar erscheinen.</li>
	<li>Nickel (II)-Chlorid-Hexahydrat in HPLC Grade Wasser zu einer Konzentration von 5 mM zu lösen. Die Lösung sollte Licht erscheinen grün.</li>
	<li>Eine Reaktion Ampulle 5 mL 1 mL der wässrigen BSA-Lösung hinzu und legen Sie in einem Wasserbad bei 37 oC. rühren die Mischung bei 750 u/min.</li>
	<li>Fügen Sie 0,5 mL der Nickel (II)-Chlorid-Hexahydrat-Lösung sofort die Reaktion Phiole und Mischung für 2 min hinzu. Hinweis: Die Lösung bleibt Licht grün.</li>
	<li>Fügen Sie 75 μL 1 M NaOH bis pH 12 und 2 h zu mischen. Hinweis: Die Lösung werden dunkelgelb.</li>
	<li>Lösen Sie chlorogoldsäure in HPLC Grade Wasser zu einer Konzentration von 5 mM auf.</li>
	<li>Die Reaktion Phiole 0,5 mL der wässrigen chlorogoldsäure hinzu und passen Sie den pH-Wert wieder auf 12.</li>
	<li>Rühren Sie das Reaktionsgemisch für 2 h. Hinweis: Die Lösung sollte auf eine braune Farbe zu entwickeln.</li>
</ol>4. Synthese von [Cys34-capped-BSA]-Au(III)
<ol><li>2 mg N-Ethylmaleimide (NEM) in 1 mL Phosphat gepufferte Kochsalzlösung (PBS, pH 7,4) auflösen.</li>
	<li>2 mg der BSA in 1 mL PBS-NEM Lösung zu lösen.</li>
	<li>Die Lösung zu einem 5 mL Reaktion Fläschchen zu übertragen und bei 20 ° C bei 500 u/min für 1 h rühren.</li>
	<li>Dialyse der Lösung mit 12 kDa Dialyse Schläuche in 500 mL PBS, bei 50 u/min unter Rühren mit einem Magnetrührer über Nacht nicht umgesetztes NEM entfernen.</li>
	<li>Lösen Sie chlorogoldsäure mit PBS-Puffer zu einer Konzentration von 0,4 mM auf. Hinweis: Die Lösung wird ein schwaches gelb sein.</li>
	<li>Übertragung der Reaktion Fläschchen in einem Wasserbad bei 37 ° C. Bei 750 u/min rühren.</li>
	<li>Sofort die Reaktion Ampulle 1 mL Chloroauric Säure-Lösung hinzufügen und für 2 min mischen lassen.</li>
	<li>Das Fläschchen Reaktion den pH 12 und für 2 h mischen fügen Sie 75 μL 1 M NaOH hinzu.</li>
</ol>5. Synthese von [all-thiol-capped-BSA]-Au(III)
<ol><li>Bereiten Sie eine Lösung von 2 M Harnstoff und 50 mM Ammonium Bicarbonat (NH4HCO3, pH 8,0) in HPLC Grade Wasser.</li>
	<li>3,3 mg der BSA in 1 mL der obigen Lösung und Transfer zu einem 5 mL-Fläschchen Reaktion auflösen.</li>
	<li>Machen Sie eine Stammlösung von 0,25 M tris(2-carboxyethyl) Phosphin (DÄMMUND) durch DÄMMUND 62,5 mg in 1 mL HPLC Wasser auflösen.</li>
	<li>Die Reaktion Phiole fügen Sie der Stammlösung DÄMMUND bis die Endkonzentration von DÄMMUND 8 mM ist hinzu.</li>
	<li>Inkubieren Sie die Lösung in einem Wasserbad für 1 h bei 50 ° c Rühren Sie bei 500 u/min mit einem Magnetrührer.</li>
	<li>Lassen Sie die Lösung vollständig auf Zimmertemperatur abkühlen.</li>
	<li>Bereiten Sie eine Stammlösung von 100 mM NEM durch NEM 12,5 mg in 1 mL HPLC Grade Wasser auflösen.</li>
	<li>Die Reaktion Phiole fügen Sie der Stammlösung von NEM bis die Endkonzentration von NEM 16 mM ist hinzu.</li>
	<li>Lassen Sie die Lösung verbinden für 2 h bei 20 ° C. Bei 500 u/min rühren.</li>
	<li>Dialyse die Lösung unter Verwendung eines 12 kDa Dialyse Schlauchs, rühren die Lösung bei 50 u/min mit einem Magnetrührer über Nacht in 500 mL 50 mM NH4HCO3 , überschüssige DÄMMUND, NEM und Harnstoff zu entfernen.</li>
	<li>Bewegen Sie die Reaktion Phiole in einem Wasserbad bei 37 ° C und bei 750 u/min rühren.</li>
	<li>Chlorogoldsäure in HPLC Grade Wasser zu einer Konzentration von 0,66 mM auflösen.</li>
	<li>Sofort die Reaktion Ampulle 1 mL Chloroauric Säure-Lösung hinzufügen und für 2 min mischen lassen.</li>
	<li>Fügen Sie 1 M NaOH bis pH der Lösung 12 und lassen Sie die Lösung weiterhin für 2 h mischen.</li>
</ol>

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Die Autoren haben nichts preisgeben.

Die BSA-Au(III) Verbindungen vorbereitet bei pH 12 weisen rote Fluoreszenz bei einer Emissionswellenlänge λEm= 640 nm bei Erregung mit ultravioletten (UV) Licht λex= 365 nm (Abbildung 1A). Die Entstehung der rote Fluoreszenz ist ein langsamer Prozess und dauert ein paar Tage bei Raumtemperatur bis zu einer maximalen Intensität zu erhöhen. Läuft die Reaktion bei 37 ° C wird die optimale Ergebnisse liefern, obwohl höherer Temperatur verwendet werden kann,...

Eine BSA-Au-Verbindung Ausstellen einer Ultraviolett (UV)-leicht erregbaren rote Fluoreszenz, mit bemerkenswerten schürt Verschiebung, wurde ursprünglich von Xie Et al.synthetisiert worden. 1. einzigartige und stabile rote Fluoreszenz finden Sie verschiedene Anwendungen in den Bereichen Fernerkundung,2,3,4, bildgebenden5,6,7oder Nanomedizin8 ,9,10,11,12,13. Diese Verbindung wurde von vielen Forschern auf dem Gebiet der Nano-Wissenschaft in den letzten Jahren14,15,16ausgiebig untersucht. Die BSA-Au-Verbindung wurde als Au25 nanocluster interpretiert. Das Ziel der vorgestellten Methode ist, diese Verbindung im Detail zu untersuchen und zu verstehen, die Herkunft der rote Fluoreszenz. Den vorgestellten Ansatz folgend können das Vorhandensein von mehreren Au Bindungsstellen, und die Herkunft der Fluoreszenz, Alternative zu einem Standort Nukleation von Au25 nanocluster dargestellt werden. Der gleiche Ansatz kann eingesetzt werden, zu studieren, wie andere Proteine17,18,19 komplexiert mit Au(III) ihren fluoreszierenden Eigenschaften ändern können.
Die Synthese der BSA-Au rot fluoreszierende Verbindung erfordert eine enge Kontrolle über das molare Verhältnis von BSA, Au (BSA:Au), die Intensität der Fluoreszenz und die Lage der Gipfel der Erregung-Emission Karte (EEM)20zu maximieren. Es kann gezeigt werden, dass mehrere Bindungsstellen für Au(III) zu binden, gibt es einschließlich der Asparagin-Fragment (oder Asp-Fragment, die ersten vier Aminosäurereste am N-Terminus des BSA)21,22. Die 34th Aminosäure der BSA (Cys-34) zeigt sich auch, Au(III) zu koordinieren und in den Mechanismus der roten fluorescence([Cys34-capped-BSA]-Au(III))20einbezogen werden. Auf alle Cys-Cys-Disulfid-Bindungen zu Spalten und verschließen alle Thiole, rote Fluoreszenz ist nicht produziert ([all-thiol-capped-BSA]-Au(III)). Dies weist auf die Notwendigkeit der Cys-Cys Disulfid Anleihen als die Au(III)-Bindungsstelle, die rote Fluoreszenz zu produzieren.
Protein-Chemie-Techniken haben nicht weit verbreitet, um die BSA-Au(III)-komplexe in der Nano-Science-Community zu studieren. Allerdings wäre es wertvoll, um diese Techniken zu verstehen, bestimmte Aspekte dieser komplexe, Detailwissen über die Au(III)-Bindungsstellen im BSA zu gewinnen. Dieser Artikel soll einige dieser Techniken zu zeigen.

<table>
	<tbody>
		<tr>
			<td>Bovine Serum Albumin (BSA), 96%</td>
			<td>Sigma-Aldrich</td>
			<td>A5611</td>
			<td></td>
		</tr>
		<tr>
			<td>gold (III) chloride trihydrate, 99.9%</td>
			<td>Sigma-Aldrich</td>
			<td>520918</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper (II) chloride dihydrate, 99.999%</td>
			<td>Sigma-Aldrich</td>
			<td>459097</td>
			<td></td>
		</tr>
		<tr>
			<td>Nickel (II) chloride hexahydrate, 99.9%</td>
			<td>Sigma-Aldrich</td>
			<td>654507</td>
			<td></td>
		</tr>
		<tr>
			<td>N-Ethylmaleimide (NEM), &#62;99.0%</td>
			<td>Sigma-Aldrich</td>
			<td>4259</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris(2-carboxyethyl)phosphine hydrochloride (TCEP), &#62;98.0%</td>
			<td>Sigma-Aldrich</td>
			<td>C4706</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide, &#62;98.0%</td>
			<td>Sigma-Aldrich</td>
			<td>S8045</td>
			<td></td>
		</tr>
		<tr>
			<td>Urea, 99.5%</td>
			<td>Chem-Implex Int&#39;l</td>
			<td>30142</td>
			<td></td>
		</tr>
		<tr>
			<td>Phospate buffered saline (PBS)</td>
			<td>Corning</td>
			<td>MT21040CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium bicarbonate, 99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>9830</td>
			<td></td>
		</tr>
	</tbody>
</table>

luminophore formation in various conformations of bovine serum albumin by binding of gold(iii)

Die vorgestellten Protokolle soll den Prozess der Au(III) Bindung an die BSA, nachgiebig Konformation bedingte rote Fluoreszenz (λEm = 640 nm) der BSA-Au(III)-komplexe. Die Methode stellt den pH-Wert zu zeigen, dass die Entstehung der rote Fluoreszenz mit der pH-induzierte Gleichgewicht Übergänge von der BSA Konformationen korreliert ist. Rot fluoreszierende BSA-Au(III)-komplexe können nur mit einer Einstellung des pH-Wertes bei oder über 9,7, das entspricht der "A-Form" Konformation der BSA gebildet werden. Das Protokoll die BSA, Au Molverhältnis anpassen und den zeitlichen Verlauf des Prozesses der Au(III) Bindung zu überwachen ist beschrieben. Die minimale Anzahl von Au(III) pro BSA, der rote Fluoreszenz zu produzieren ist weniger als sieben. Wir beschreiben das Protokoll in Schritten, um das Vorhandensein von mehreren Au(III)-Bindungsstellen im BSA zu veranschaulichen. Erstens, durch Zugabe von Kupfer (Cu(II)) oder Nickel (Ni(II)) kationen gefolgt von Au(III), zeigt diese Methode eine Bindungsstelle für Au(III), die nicht das rote Fluorophor. Zweitens wird durch BSA von Thiol Deckelung Agenten ändern, ein anderes Nonfluorophore bilden Au(III) Bindungsstelle aufgedeckt. Drittens sind ändern die BSA-Konformation durch Spaltung und Begrenzung der Disulfid-Bindungen, die mögliche Au(III) Bindung Webseite(n) illustriert. Das Protokoll beschrieben, zur Steuerung der BSA Konformationen und Au(III) Bindung, kann in der Regel angewendet werden, um die Wechselwirkungen von anderen Proteinen und Metallkationen zu studieren.

Aus der Fluoreszenz des BSA-Au(III) komplexes, es wurde beobachtet, dass die Umwandlung der inneren blauen Fluoreszenz der BSA (λEm = 400 nm), rote Fluoreszenz (λEm = 640 nm) tritt bei etwa pH 9,7 durch ein Gleichgewicht Übergang (Abbildung 1). EEM BSA-Au(III) bei verschiedenen BSA Au molare Verhältnis ist in Abbildung 2dargestellt, und diese Daten zeigt, wie die gleichen Emissionswelle...

Watch this Scientific Journal Video about Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII at JoVE.com

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII

Die Protokolle für das Studium der Bindung von gold-Kationen (Au(III)) zu verschiedenen Konformationen der Rinderserumalbumin (BSA) wie auch für die Charakterisierung der Konformationsänderungen abhängigen einzigartige BSA-Au Fluoreszenz dargestellt werden.

Luminophor Bildung in verschiedenen Konformationen von Rinderserumalbumin durch Bindung von Gold(III)

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em ...

luminophore-formation-various-conformations-bovine-serum-albumin

Research

JoVE Journal

Chemistry

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

6.8K Aufrufe.  University of North Carolina. Die Protokolle für das Studium der Bindung von gold-Kationen (Au(III)) zu verschiedenen Konformationen der Rinderserumalbumin (BSA) wie auch für die Charakterisierung der Konformationsänderungen abhängigen einzigartige BSA-Au Fluoreszenz dargestellt werden.

Serie: Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII

LabVIEW-operated Novel Nanoliter Osmometer for Ice Binding Protein Investigations

Ice-binding proteins (IBPs), including antifreeze proteins, ice structuring proteins, thermal hysteresis proteins, and ice recrystallization inhibition proteins, are found in cold-adapted organisms and protect them from freeze injuries by interacting with ice crystals. IBPs are found in a variety of organism, including fish1, plants2, 3, arthropods4, 5, fungi6, and bacteria7. IBPs adsorb to the surfaces of ice crystals and prevent water molecules from joining the ice lattice at the IBP adsorption location. Ice that grows on the crystal surface between the adsorbed IBPs develops a high curvature that lowers the temperature at which the ice crystals grow, a phenomenon referred to as the Gibbs-Thomson effect. This depression creates a gap (thermal hysteresis, TH) between the melting point and the nonequilibrium freezing point, within which ice growth is arrested8-10, see Figure 1. One of the main tools used in IBP research is the nanoliter osmometer, which facilitates measurements of the TH activities of IBP solutions. Nanoliter osmometers, such as the Clifton instrument (Clifton Technical Physics, Hartford, NY,) and Otago instrument (Otago Osmometers, Dunedin, New Zealand), were designed to measure the osmolarity of a solution by measuring the melting point depression of droplets with nanoliter volumes. These devices were used to measure the osmolarities of biological samples, such as tears11, and were found to be useful in IBP research. Manual control over these nanoliter osmometers limited the experimental possibilities. Temperature rate changes could not be controlled reliably, the temperature range of the Clifton instrument was limited to 4,000 mOsmol (about -7.5 &deg;C), and temperature recordings as a function of time were not an available option for these instruments.
We designed a custom-made computer-controlled nanoliter osmometer system using a LabVIEW platform (National Instruments). The cold stage, described previously9, 10, contains a metal block through which water circulates, thereby functioning as a heat sink, see Figure 2. Attached to this block are thermoelectric coolers that may be driven using a commercial temperature controller that can be controlled via LabVIEW modules, see Figure 3. Further details are provided below. The major advantage of this system is its sensitive temperature control, see Figure 4. Automated temperature control permits the coordination of a fixed temperature ramp with a video microscopy output containing additional experimental details.
To study the time dependence of the TH activity, we tested a 58 kDa hyperactive IBP from the Antarctic bacterium Marinomonas primoryensis (MpIBP)12. This protein was tagged with enhanced green fluorescence proteins (eGFP) in a construct developed by Peter Davies' group (Queens University)10. We showed that the temperature change profile affected the TH activity. Excellent control over the temperature profile in these experiments significantly improved the TH measurements. The nanoliter osmometer additionally allowed us to test the recrystallization inhibition of IBPs5, 13. In general, recrystallization is a phenomenon in which large crystals grow larger at the expense of small crystals. IBPs efficiently inhibit recrystallization, even at low concentrations14, 15. We used our LabVIEW-controlled osmometer to quantitatively follow the recrystallization of ice and to enforce a constant ice fraction using simultaneous real-time video analysis of the images and temperature feedback from the sample chamber13. The real-time calculations offer additional control options during an experimental procedure. A stage for an inverted microscope was developed to accommodate temperature-controlled microfluidic devices, which will be described elsewhere16.
The Cold Stage System
The cold stage assembly (Figure 2) consists of a set of thermoelectric coolers that cool a copper plate. Heat is removed from the stage by flowing cold water through a closed compartment under the thermoelectric coolers. A 4 mm diameter hole in the middle of the copper plate serves as a viewing window. A 1 mm diameter in-plane hole was drilled to fit the thermistor. A custom-made copper disc (7 mm in diameter) with several holes (500 &mu;m in diameter) was placed on the copper plate and aligned with the viewing window. Air was pumped at a flow rate of 35 ml/sec and dried using Drierite (W.A. Hammond). The dry air was used to ensure a dry environment at the cooling stage. The stage was connected via a 9 pin connection outlet to a temperature controller (Model 3040 or 3150, Newport Corporation, Irvine, California, US). The temperature controller was connected via a cable to a computer GPIB-PCI card (National instruments, Austin, Texas, USA).

Ice binding proteins (IBPs), also known as antifreeze proteins, inhibit ice growth and are a promising additive for use in the cryopreservation of tissues. The main tool used to investigate IBPs is the nanoliter osmometer. We developed a home-designed cooling stage mounted on an optical microscope and controlled using a custom-built LabVIEW routine. The nanoliter osmometer described here manipulated the sample temperature in an ultra-sensitive manner.

LabVIEW-betriebenen Novel Nanoliter Osmometer für Ice Binding Protein Untersuchungen

Ice-binding proteins (IBPs), including antifreeze proteins, ice structuring proteins, thermal hysteresis proteins, and ice recrystallization inhibition ...

Forschung

Chemie

Large Scale Non-targeted Metabolomic Profiling of Serum by Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS)

Non-targeted metabolite profiling by ultra performance liquid chromatography coupled with mass spectrometry (UPLC-MS) is a powerful technique to investigate metabolism. The approach offers an unbiased and in-depth analysis that can enable the development of diagnostic tests, novel therapies, and further our understanding of disease processes. The inherent chemical diversity of the metabolome creates significant analytical challenges and there is no single experimental approach that can detect all metabolites. Additionally, the biological variation in individual metabolism and the dependence of metabolism on environmental factors necessitates large sample numbers to achieve the appropriate statistical power required for meaningful biological interpretation. To address these challenges, this tutorial outlines an analytical workflow for large scale non-targeted metabolite profiling of serum by UPLC-MS. The procedure includes guidelines for sample organization and preparation, data acquisition, quality control, and metabolite identification and will enable reliable acquisition of data for large experiments and provide a starting point for laboratories new to non-targeted metabolite profiling by UPLC-MS.

Large Scale Non-targeted Metabolomic Profiling of Serum by Ultra Performance Liquid Chromatography-Mass Spectrometry UPLC-MS

Non-targeted metabolite profiling by ultra performance liquid chromatography coupled with mass spectrometry (UPLC-MS) is a powerful technique to investigate metabolism. This article outlines a typical workflow utilized for non-targeted metabolite profiling of serum including sample organization and preparation, data acquisition, data analysis, quality control, and metabolite identification.

Large Scale Non gezielte Metabolomic Profiling von Serum von Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS)

Non-targeted metabolite profiling by ultra performance liquid chromatography coupled with mass spectrometry (UPLC-MS) is a powerful technique to ...

Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell differentiation into osteoblasts, thus stimulating healing and de novo bone formation. The clinical use of recombinant human BMP-2 (rhBMP-2) in conjunction with scaffolds has raised recent controversies, based on the mode of presentation and the amount to be delivered. The protocol presented here provides a simple and efficient way to deliver BMP-2 for in vitro studies on cells. We describe how to form a self-assembled monolayer consisting of a heterobifunctional linker, and show the subsequent binding step to obtain covalent immobilization of rhBMP-2. With this approach it is possible to achieve a sustained presentation of BMP-2 while maintaining the biological activity of the protein. In fact, the surface immobilization of BMP-2 allows targeted investigations by preventing unspecific adsorption, while reducing the amount of growth factor and, most notably, hindering uncontrolled release from the surface. Both short- and long-term signaling events triggered by BMP-2 are taking place when cells are exposed to surfaces presenting covalently immobilized rhBMP-2, making this approach suitable for in vitro studies on cell responses to BMP-2 stimulation.

We describe a method for accomplishing efficient immobilization of BMP-2 on surfaces. Our approach is based on the formation of a self-assembled monolayer to achieve the covalent binding of BMP-2 via its free amine residues. This method is a useful tool to study signaling at the cell membrane.

Die kovalente Bindung von BMP-2 auf Oberflächen mit einem selbstorganisierten Monoschicht-Ansatz

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell ...

Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large variety of PEG molecular weights and configurations (arm number, arm length, and branching pattern) affords researchers tight control over resulting hydrogel structures and properties, including Young&#8217;s modulus and mesh size. This video will illustrate a rapid, efficient, solvent-free, microwave-assisted method to methacrylate PEG precursors into poly(ethylene glycol) dimethacrylate (PEGDM). This synthetic method provides much-needed starting materials for applications in drug delivery and regenerative medicine. The demonstrated method is superior to traditional methacrylation methods as it is significantly faster and simpler, as well as more economical and environmentally friendly, using smaller amounts of reagents and solvents. We will also demonstrate an adaptation of this technique for on-resin methacrylamide functionalization of peptides. This on-resin method allows the N-terminus of peptides to be functionalized with methacrylamide groups prior to deprotection and cleavage from resin. This allows for selective addition of methacrylamide groups to the N-termini of the peptides while amino acids with reactive side groups (e.g.&#160;primary amine of lysine, primary alcohol of serine, secondary alcohols of threonine, and phenol of tyrosine) remain protected, preventing functionalization at multiple sites. This article will detail common analytical methods (proton Nuclear Magnetic Resonance spectroscopy (;H-NMR) and Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-ToF)) to assess the efficiency of the functionalizations. Common pitfalls and suggested troubleshooting methods will be addressed, as will modifications of the technique which can be used to further tune macromer functionality and resulting hydrogel physical and chemical properties. Use of synthesized products for the formation of hydrogels for drug delivery and cell-material interaction studies will be demonstrated, with particular attention paid to modifying hydrogel composition to affect mesh size, controlling hydrogel stiffness and drug release.

Microwave-assisted Functionalization of Polyethylene glycol and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

This video will illustrate a rapid, efficient method to methacrylate poly(ethylene glycol), enabling chain polymerizations and hydrogel synthesis. It will demonstrate how to similarly introduce methacrylamide functionalities into peptides, detail common analytical methods to assess functionalization efficiency, provide suggestions for troubleshooting and advanced modifications, and demonstrate typical hydrogel characterization techniques.

Mikrowellen-unterstützte Funktionalisierung von Poly (Ethylenglycol) und On-Harz Peptide zur Verwendung in Kettenpolymerisationen und Hydrogelierung

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large ...

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

Bildung geordneter Strukturen Biomolekulare durch die Selbstorganisation von kurzen Peptiden

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity

Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice through their ice-binding surfaces. Fluorescence-based ice plane affinity (FIPA) analysis is a modified technique used to determine the ice planes to which the AFPs bind. FIPA is based on the original ice-etching method for determining AFP-bound ice-planes. It produces clearer images in a shortened experimental time. In FIPA analysis, AFPs are fluorescently labeled with a chimeric tag or a covalent dye then slowly incorporated into a macroscopic single ice crystal, which has been preformed into a hemisphere and oriented to determine the a- and c-axes. The AFP-bound ice hemisphere is imaged under UV light to visualize AFP-bound planes using filters to block out nonspecific light. Fluorescent labeling of the AFPs allows real-time monitoring of AFP adsorption into ice. The labels have been found not to influence the planes to which AFPs bind. FIPA analysis also introduces the option to bind more than one differently tagged AFP on the same single ice crystal to help differentiate their binding planes. These applications of FIPA are helping to advance our understanding of how AFPs bind to ice to halt its growth and why many AFP-producing organisms express multiple AFP isoforms.

Antifreeze proteins (AFPs) bind to specific planes of ice to prevent or slow ice growth. Fluorescence-based ice plane affinity (FIPA) analysis is a modification of the original ice-etching method for determination of AFP-bound ice planes. AFPs are fluorescently labeled, incorporated into macroscopic single ice crystals, and visualized under UV light.

Bestimmung der eisbindenden Ebenen von Frostschutzproteinen durch Fluoreszenzbasierte Eisebene Affinität

Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice ...

Water in Oil Emulsions: A New System for Assembling Water-soluble Chlorophyll-binding Proteins with Hydrophobic Pigments

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. Their functionality critically depends on their specific organization within large and elaborate multisubunit transmembrane protein complexes. In order to understand at the molecular level how these complexes facilitate solar energy conversion, it is essential to understand protein-pigment, and pigment-pigment interactions, and their effect on excited dynamics. One way of gaining such understanding is by constructing and studying complexes of Chls with simple water-soluble recombinant proteins. However, incorporating the lipophilic Chls and BChls into water-soluble proteins is difficult. Moreover, there is no general method, which could be used for assembly of water-soluble proteins with hydrophobic pigments. Here, we demonstrate a simple and high throughput system based on water-in-oil emulsions, which enables assembly of water-soluble proteins with hydrophobic Chls. The new method was validated by assembling recombinant versions of the water-soluble chlorophyll binding protein of Brassicaceae plants (WSCP) with Chl a. We demonstrate the successful assembly of Chl a using crude lysates of WSCP expressing E. coli cell, which may be used for developing a genetic screen system for novel water-soluble Chl-binding proteins, and for studies of Chl-protein interactions and assembly processes.

This manuscript describes a simple and high-throughput method for assembling water-soluble proteins with hydrophobic pigments that is based on water-in-oil emulsions. We demonstrate the effectiveness of the method in the assembly of native chlorophylls with four variants of recombinant water-soluble-chlorophyll binding proteins (WSCPs) of Brassica plants expressed in E. coli.

Wasser in Öl-Emulsionen: Ein neues System für die Montage wasserlösliche Chlorophyll-bindenden Proteine ​​mit hydrophober Pigments

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. ...

Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation

Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular identity and function. Each of the seven PtdInsPs varies in their distribution and abundance, which are tightly regulated by specific kinases and phosphatases. The abundance of PtdInsPs can change abruptly in response to various signaling events or disturbance of the regulatory machinery. To understand how these events lead to changes in the amount of PtdInsPs and their resulting impact, it is important to quantify PtdInsP levels before and after a signaling event or between control and abnormal conditions. However, due to their low abundance and similarity, quantifying the relative amounts of each PtdInsP can be challenging. This article describes a method for quantifying PtdInsP levels by metabolically labeling cells with 3H-myo-inositol, which is incorporated into PtdInsPs. Phospholipids are then precipitated and deacylated. The resulting soluble 3H-glycero-inositides are further extracted, separated by high-performance liquid chromatography (HPLC), and detected by flow scintillation. The labeling and processing of yeast samples is described in detail, as well as the instrumental setup for the HPLC and flow scintillator. Despite losing structural information regarding acyl chain content, this method is sensitive and can be optimized to concurrently quantify all seven PtdInsPs in cells.

Phosphoinositides are signaling lipids whose relative abundance rapidly changes in response to various stimuli. This article describes a method to measure the abundance of phosphoinositides by metabolically labeling cells with 3H-myo-inositol, followed by extraction and deacylation. Extracted glycero-inositides are then separated by high-performance liquid chromatography and quantified by flow scintillation.

Radiomarkierung und Quantifizierung von Cellular Ebenen Phosphoinositide von High Performance Liquid Chromatography-gekoppelten Durchflussscintilla

Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular ...

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum Interface (SALVI) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The fibronectin protein film was immobilized on the silicon nitride (SiN) membrane that forms the SALVI detection area. During ToF-SIMS analysis, three modes of analysis were conducted including high spatial resolution mass spectrometry, two-dimensional (2D) imaging, and depth profiling. Mass spectra were acquired in both positive and negative modes. Deionized water was also analyzed as a reference sample. Our results show that the fibronectin film in water has more distinct and stronger water cluster peaks compared to water alone. Characteristic peaks of amino acid fragments are also observable in the hydrated protein ToF-SIMS spectra. These results illustrate that protein molecule adsorption on a surface can be studied dynamically using SALVI and ToF-SIMS in the liquid environment for the first time.

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work presents a protocol for liquid handling and sample introduction to a microchannel for in situ time-of-flight secondary ion mass spectrometry analysis of protein biomolecules in an aqueous solution.

In-situ-Charakterisierung von Hydrated Proteine ​​in Wasser durch SALVI und TOF-SIMS

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum ...

DNA-magnetic Particle Binding Analysis by Dynamic and Electrophoretic Light Scattering

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the evaluation of DNA-magnetic particles binding via dynamic light scattering (DLS) and electrophoretic light scattering (ELS). Analysis by DLS provides valuable information on the physicochemical properties of particles including particle size, polydispersity, and zeta potential. The latter describes the surface charge of the particle which plays major role in electrostatic binding of materials such as DNA. Here, a comparative analysis exploits three chemical modifications of nanoparticles and microparticles and their effects on DNA binding and elution. Chemical modifications by branched polyethylenimine, tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane are investigated. Since DNA exhibits a negative charge, it is expected that zeta potential of particle surface will decrease upon binding of DNA. Forming of clusters should also affect particle size. In order to investigate the efficiency of these particles in isolation and elution of DNA, the particles are mixed with DNA in low pH (~6), high ionic strength and dehydration environment. Particles are washed on magnet and then DNA is eluted by Tris-HCl buffer (pH = 8). DNA copy number is estimated using quantitative polymerase chain reaction (PCR). Zeta potential, particle size, polydispersity and quantitative PCR data are evaluated and compared. DLS is an insightful and supporting method of analysis that adds a new perspective to the process of screening of particles for DNA isolation.

This protocol describes the synthesis of magnetic particles and evaluation of their DNA-binding properties via dynamic and electrophoretic light scattering. This method focuses on monitoring changes in particle size, their polydispersity and zeta potential of particle surface which play major role in binding of materials such as DNA.

DNA-Magnetpartikel verbindlich Analyse durch dynamische und elektrophoretische Lichtstreuung

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the ...