Die Autoren danken Herrn Luis F. Delgadillo (Department of Chemical and Biomolecular Engineering, Ohio University), Herrn Matthew H. Williams (Department of Chemical and Biomolecular Engineering, Ohio University) und Dr. Filiberto Cedeno-Laurent (Brigham and Women es Hospital und Harvard Medical School) für die technische Unterstützung von Experten. Die Autoren danken auch den Studenten des Winter 2011 CHE 404/BME 504 und des Herbst 2012 CHE 4830/BME 5830 (Department of Chemical and Biomolecular Engineering and Biomedical Engineering Program, Ohio University) für technische Beratung und Diskussion. Diese Arbeit wurde unterstützt durch das Major Research Instrumentation Grant CBET-1039869 (MMB), NSF CBET-1106118 (MMB), Dermatology Foundation Research Grant A050422 (SRB), National Institutes of Health (NIH) NCI Grant 1R15CA1 61830-01 (MMB), NIH Kirschstein-NRSA Postdoktorandenstipendium F32CA144219-01A1 (SRB), NIH/NCI R01CA173610 (CJD) und NIH NCCAM-Stipendium R01AT004628 (CJD).

1. Überprüfen Sie die Affinität für Protein A
<ol><li>Stellen Sie sicher, dass das Fc-exporierende Protein (rekombinantes Fusionsprotein oder IgG-Antikörper, bisher als "Protein" bezeichnet) eine akzeptable Affinität zu Protein A14-17 vor der Verwendung des Proteins A Membranadsorber hat, und testen Sie das Vorhandensein des Proteins in der Stammlösung(z. B. Zellkulturüberstand, der durch Zentrifugation bei 1.000 x g für 5 min zu einem). Verwenden Sie Durchflusszytometrie, Western Blotting, ELISA usw. Proteinfunktion und/oder Vorhandensein von Fc auf der Grundlage von Laborpräferenzen zu erkennen. Im Idealfall quantifizieren Sie das Protein in der Zellkultur Überstand (Schritt 6), um eine Überschreitung der Protein-A-Membranadsorberkapazität zu vermeiden. Fahren Sie fort, wenn Protein nachgewiesen wird.</li>
</ol>2. Bereiten Protein A Membran Adsorber und Zellkultur Supernatant
<ol><li>Befolgen Sie die Anweisungen des Herstellers zur Herstellung des Membranadsorbers. Lassen Sie niemals Luft in den Membranadsorber eindringen. Alle Lösungen, die durch den Membranadsorber durchsetzt werden, sollten bei Raumtemperatur sein und mit einem 0,22 m-Filter vorgefiltert werden. Füllen Sie eine 10 ml Spritze mit 0,22 m-gefilterter Dulbecco-Phosphat-gepufferter Saline (DPBS) oder Puffer nach Wahl und entleeren Luftblasen. Durchdringen Sie DPBS, um die Speicherlösung zu entfernen und den Membranadsorber unmittelbar vor der Anwendung auszudemt.</li>
	<li>Filtern Sie den Zellkulturüberstand unmittelbar vor der Perfusion durch den Membranadsorber, indem Sie eine vakuumgesteuerte sterile Filtrationseinheit mit 0,22 m verwenden.</li>
</ol>3. Laden Sie das Protein A Membrane Adsorber
<ol><li>Aspirieren Zellkultur Überstand in eine Luer Lock Spritze (30 ml oder größer), und entladen Alle Luftblasen.</li>
	<li>Montieren Sie Materialien und Ausrüstungen, wie in Abbildung 1dargestellt. Schließen Sie die Spritze an den Einlass des Membranadsorbers an. Befestigen Sie flexible Schläuche am Membranadsorberauslass. Legen Sie auf Wunsch einen Spritzenfilter von 0,22 m zwischen die Spritze und den Membranadsorber. Verwenden Sie einen Kolben oder eine Flasche, um den Durchfluss (auch als Filtrat bezeichnet) vom Adsorber zu fangen.</li>
	<li>Stellen Sie die Spritzenpumpe auf den gewünschten Volumendurchfluss ein, überschreiten Sie jedoch nicht den vom Hersteller empfohlenen Durchfluss(z. B. 10 ml/min). Durchdringen Sie die Zellkultur, die durch den Membranadsorber durchläuft, und sammeln Sie den Durchfluss in einem Becher oder einem anderen Behälter. Laden Sie die Spritze mit den erforderlichen Überstanden nach.</li>
	<li>Auf Wunsch testen Sie den Durchfluss auf das Vorhandensein von Protein entoverwendend, indem Sie Diedurchflusszytometrie, Western Blotting, ELISA usw.verwenden. basierend auf labor-Präferenz. Es ist in der Regel nicht erforderlich, den Durchfluss durchzuspielen.</li>
</ol>4. Elute Protein aus dem Membranadsorber
<ol><li>Waschen Sie den Membranadsorber mit 10 ml DPBS, um alle nicht gebundenen Proteine zu entfernen.</li>
	<li>Elute-Protein aus dem Membranadsorber bei der gewünschten Durchflussrate(z.B. 1 ml/min) mit 10-15 ml Elutionspuffer(z.B. Amin-basierter Elutionspuffer (pH 2,8)). Fangen Sie eluat in einem Rohr mit Neutralisationspuffer(z. B. 1 M Tris (pH 9.4)) bei 10% des Elutionsvolumens (1,0-1,5 ml).</li>
	<li>Alternativ wird elute Protein in einem ml in Tuben mit einem Neutralisationspuffer von 100 l mit einem Gesamtvolumen von 10-15 ml Elutionspuffer erhöht. Verwenden Sie die bevorzugte Charakterisierungsmethode, um jede Fraktion auf das Vorhandensein von Protein zu testen.</li>
	<li>Regenerieren Sie den Membranadsorber gemäß den Anweisungen des Herstellers. Durchdringen Sie 10 ml 0,22 m-gefilterte DPBS oder Puffer nach Wahl, dann 10 ml 0,22 m-gefilterte 50 mM NaOH in 1 N NaCl und schließlich 10 ml 0,22 m-gefiltertes DPBS. Füllen Sie den Membranadsorber mit 20% Ethanol in DPBS für die Langzeitlagerung bei 4 oC.</li>
</ol>5. Konzentrieren und Dialyse das Protein
<ol><li>Legen Sie alle Eluate (oder Elutionsfraktionen, die Protein enthalten, wie in Schritt 4.3 bestimmt) in einer 10 kDa Molekulargewichts-Trennzentrifugalfiltereinheit abzulegen. Befolgen Sie die Anweisungen des Herstellers für die Zentrifugation.</li>
	<li>Dialysieren Sie das Retentat in einer dialysatenkleinen Dialyseeinheit (10 kDa Molekulargewichtsabschaltung) nach den Anweisungen des Herstellers gegen den Puffer der Wahl. Wenn die Proteinfällung anlasse, muss dem Dialysematerial ein Puffer hinzugefügt werden. Auf Wunsch kann das Dialysematerial bis Schritt 6 gekühlt werden, eine Langzeitlagerung ohne Konservierungsstoffe wird jedoch nicht empfohlen.</li>
</ol>6. Quantifizieren und Charakterisieren von gereinigtem Produkt in einem beschleunigten Western Blotting-Verfahren
<ol><li>Lösen Sie gereinigte Protein- und Fc-Standards auf dem Gel der Wahl von SDS-PAGE, unter reduzierenden oder nicht reduzierenden Bedingungen wie gewünscht18-20. Verwenden Sie ein Mini-Gel anstelle von Midi-Gel, um die Laufzeit zu minimieren.<ol>
<li>Wenn nicht bereits bekannt, bestimmen Sie den Fc-Normbereich, über den das Bandsignal in Bezug auf die Menge der geladenen(z. B. 0,1-1 mg) linear variiert. Verwenden Sie das gleiche Gel, Laufbedingungen, Transferbedingungen und Reagenzien, die verwendet werden, um gereinigtes Protein zu quantifizieren und zu charakterisieren.</li>
			<li>Laden Sie mehrere Probenmengen an gereinigtem Protein, einschließlich probenverdünnt mit DPBS, um sicherzustellen, dass die gereinigten Proteinbandsignale innerhalb des linearen Signalbereichs der Fc-Standards in der Bildanalyse liegen.</li>
		</ol>
</li>
	<li>Übertragen Sie Proteine aus dem Gel auf eine Polyvinylidenfluorid-Membran (PVDF) in einem diskontinuierlichen Puffersystem mit einem semidry blotter13, entsprechend den Anweisungen des Blotterherstellers. Die Transferzeit beträgt in der Regel 5-10 min. Wenn gewünscht, Coomassie Färben sie das Gel nach der Übertragung, um Transfer-Effizienz zu überprüfen21.</li>
	<li>Durchführung von Immunoblotting mit Anti-Fc oder Anti-IgG konjugiert zu alkalischer Phosphatase (AP) oder Pferderettichperoxidase (HRP), basierend auf Laborpräferenz, mit einem vakuumunterstützten Proteinnachweissystem. Immunoblotting Zeit ist in der Regel weniger als 1 Stunde.</li>
	<li>Entwickeln Sie Immunoblot mit dem Substrat und der Methode ihrer Wahl(z. B. AP-Substrat und verbesserte Chemilumineszenz).</li>
	<li>Quantifizieren Sie gereinigtes Protein durch Bildanalyse. Führen Sie eine lineare Regression der Bandsignale von Fc-Standards durch. WennR2>0,90, verwenden Sie die Gleichung für die Linie, um die Proteinmenge aus ihren Bandsignalen zu berechnen. Ggf. Berücksichtigung der Probenverdünnung. Da die Quantifizierung des Proteins auf Basis von Fc erfolgt, passen Sie den Wert für molekulare Gewichtsunterschiede zwischen dem Protein und Fc an. WennR2<0,90, wiederholen Sie Schritt 6 in seiner Gesamtheit.</li>
	<li>Validieren Sie Protein emittiert mit funktionellen Assays oder Methoden, um Fc über Durchflusszytometrie, Western Blotting, ELISA usw.zu erkennen. basierend auf labor-Präferenz.</li>
	<li>Protein auf die gewünschte Konzentration verdünnen und/oder gewünschte Konservierungsstoffe oder Stabilisatoren in die gereinigte Proteinlösung geben, bevor es für eine langfristige Lagerung, gefroren oder auf andere Weise aliquotiert wird.</li>
</ol>

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Es gibt nichts zu verraten.

Das hier beschriebene Protokoll wurde entwickelt, um ein chimäres Fusionsprotein, das den menschlichen Fc (Gal-1hFc) exzeichnet, schnell zu isolieren und zu charakterisieren, ohne die Produktrückgewinnung oder die Aufblähungskosten erheblich zu beeinträchtigen. Die wichtigsten Komponenten des optimierten Workflows sind ein Protein-A-Membranadsorber für die Isolierung sowie semidry transfer und vakuumunterstütztes Immunoblotting zur Charakterisierung durch Western Blotting.
Die dramatisc...

Die Isolierung von Antikörpern und rekombinanten Proteinen, die Immunglobulin G (IgG) fc-Fragmente aus Zellkulturüberstand und verdünnten lysierten Zelllösungen exemitzenen, kann mit Hilfe der Protein-A-Affinitätschromatographie erreicht werden. In wissenschaftlichen und technischen Grundlagenlaboren und der Industrie werden Säulen, die mit porösem Protein A-beschichteter Agarose, Glas oder Polymerperlen verpackt sind, am häufigsten für die Affinitätschromatographie verwendet, trotz hoher finanzieller Kosten und langer Verarbeitungszeiten1-3. Es ist sehr zu schätzen, dass die Affinitätschromatographie den größten Aufwands- und Verarbeitungsengpass sowohl im Labor als auch in der Industrie darstellt2,4. Als Ergebnis wurden zahlreiche Verbesserungen entwickelt, um Kosten und Verarbeitungszeit zu senken, ohne die gesamte Produktrückgewinnung aus dem Prozesszug1,2,5-7zu opfern. Besonders vielversprechend für die Isolierung von Antikörpern und anderen Fc-exemittierenden Proteinen ist die Affinitätschromatographie mit einem Protein A Membranadsorber2,5,7-10. Während die Fc-Capture in der Säulenchromatographie diffusionsbegrenzt ist(d.h. das Fc-extierende Protein muss in und durch die inneren Poren diffundieren, um den Großteil des Proteins A zu erreichen) mit hohem Druckabfall über die Säule, wird der Massentransport in Membranadsorbern durch Massenkonvektion angetrieben, was zur Vermeidung von Diffusionsbeschränkungen8,9,11,12führt. Darüber hinaus ist der Druckabfall über den Membranadsorber gering, was eine schnellere Durchblutung im Vergleich zu perlenverpackten Säulen8,9,11,12ermöglicht. Daher wird für die Isolierung von Laborskalen prognostiziert, dass die Membranchromatographie die Isolationszeit um mehrere Stunden reduziert und die Produkterfassung im Vergleich zur Säulenchromatographie erhöht. Darüber hinaus wurden mathematische Modelle für die IgG-Adsorption in Membranadsorbern8,9,11,12vorgeschlagen, so dass Endbenutzer die Leistung im Labor vorhersagen können.
Ein weiterer Engpass in wissenschaftlichen und technischen Grundlagenlaboren ist die Charakterisierung des Fc-exemittigen Proteins. Die Auswahl geeigneter Methoden zum Abschließen von Charakterisierungstests, wie westlichen Flecken, kann jedoch den Zeitaufwand für Produkttests erheblich reduzieren. Zum Beispiel kann die semitrockene Übertragung in einem diskontinuierlichen Puffersystem den elektrophoretischen Transfer von Proteinen von einem SDS-PAGE-Gel auf eine Polyvinyldifluoridin -Membran (PVDF) in wenigen Minuten erreichen, im Gegensatz zu 1-2 Stunden im Tank (Nasstransfer) in einem kontinuierlichen Puffersystem13.
Ein schnelles, kostengünstiges und effektives Protokoll zur Isolierung und Charakterisierung eines chimerischen Fusionsproteins, das ein Fc-Fragment menschlichen IgG ausdrückt, wird hierin beschrieben. Die meisten Geräte sind in grundlegenden biomedizinischen Grundlagen, Biologie, Chemie und (Bio-)Chemie-Engineering-Labors leicht verfügbar, und alle Reagenzien sind im Handel erhältlich. Obwohl repräsentative Ergebnisse aus der Isolierung und Charakterisierung eines murinen Galectin-1/menschlichen Fc chimeric Fusion Protein (Gal-1hFc) generiert wurden, kann das gestraffte Protokoll auf die Isolierung anderer Moleküle angewendet werden, die ein Fc-Fragment besitzen, wie Antikörper, Fc-Fragmente selbst oder andere Fc-Fusionsproteine. Unsere Verbesserungen verringerten die Verarbeitungszeit drastisch (nur 4 Stunden, aber in der Regel 9 Stunden, im Vergleich zu 20+ Arbeitsstunden) und erreichten gleichzeitig eine ähnliche oder verbesserte Produktwiederherstellung im Vergleich zu Standardmethoden.

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	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Protein A membrane adsorber (Sartobind Protein A 2 ml)&#160;</td>
			<td style="width:191px;">Sartorius-Stedim</td>
			<td style="width:147px;">93PRAP06HB-12--A</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Amicon Ultra centrifugal filter, 10 kDa, 4 ml</td>
			<td style="width:191px;">Millipore</td>
			<td>UFC801008</td>
			<td>Use 15 ml volume if needed</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Sterile vacuum filter unit, 0.22 &#181;m, 500 ml</td>
			<td>Millipore</td>
			<td>SCGPU05RE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">10 ml Syringes with Luer Lock tips</td>
			<td>BD</td>
			<td>301604</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">30 ml Syringes with&#160; Luer Lock tips</td>
			<td>BD</td>
			<td>309650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Tygon lab tubing (1/16 in x 1/8 in x 50 ft)</td>
			<td>Cole Parmer</td>
			<td>WU-95903-16</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Slide-A-Lyzer MINI Dialysis Devices (10K MWCO)</td>
			<td>Thermo Scientific</td>
			<td>69576</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Snap i.d. antibody collection tray</td>
			<td>EMD Millipore</td>
			<td>WBAVDABTR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Snap i.d. single well blot holder</td>
			<td>EMD Millipore</td>
			<td>WBAVDBH01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Elution buffer</td>
			<td>Thermo Scientific</td>
			<td>21004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Tris, ultra pure</td>
			<td>Fisher Scientific</td>
			<td>819623</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Sodium chloride</td>
			<td>Fisher Scientific</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Tween 20</td>
			<td>Fisher Scientific</td>
			<td>BP337-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">DPBS</td>
			<td>Thermo Scientific&#160;</td>
			<td>SH30028.02</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:313px;">DPBS with Ca2+/Mg2+</td>
			<td>Life Technologies</td>
			<td>14080-055</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">BSA</td>
			<td>Sigma</td>
			<td>A9647</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Human Fc</td>
			<td>Bethyl Research Laboratories</td>
			<td>&#160;P80-104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Anti-human Fc-APC</td>
			<td>Jackson Immunoresearch</td>
			<td>109136170</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Anti-human Fc-AP</td>
			<td>Bio-Rad</td>
			<td>170-5018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Alkaline phosphatase substrate</td>
			<td>Promega</td>
			<td style="width:147px;">S3841</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Flow cytometry tubes (5 ml polystyrene or polypropylene)</td>
			<td>BD</td>
			<td>352054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;"></td>
			<td style="width:191px;"></td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Name of Material/ Equipment</td>
			<td style="width:191px;">Company</td>
			<td style="width:147px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Syringe pump</td>
			<td>Harvard Apparatus</td>
			<td>55-2226</td>
			<td style="width:173px;">A peristaltic pump is also acceptable</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">Protein gel electrophoresis system&#160;</td>
			<td>Bio-Rad Laboratories</td>
			<td>552BR094876</td>
			<td style="width:173px;">Any gel electrophoresis system is acceptable, but mini gel systems run fastest</td>
		</tr>
		<tr height="126">
			<td height="126" style="height:126px;">Semidry blotter&#160;</td>
			<td>Bio-Rad Laboratories</td>
			<td style="width:147px;">690BR006163</td>
			<td style="width:173px;">Any transfer system is acceptable, but discontinuos transfer systems perform electrophoretic transfer fastest</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:313px;">SNAP i.d. vacuum-assisted protein detection system</td>
			<td style="width:191px;">EMD Millipore</td>
			<td>WBAVDBASE</td>
			<td style="width:173px;">An upgraded model has replaced this specific instrument, but either should work just as well</td>
		</tr>
	</tbody>
</table>

isolation and characterization of chimeric human fc-expressing proteins using protein a membrane adsorbers and a streamlined workflow

Laborwaage numerativ zur industriellen Reinigung von Biomolekülen aus Zellkulturüberstand und Lysed-Zell-Lösungen kann mit Affinitätschromatographie durchgeführt werden. Während die Affinitätschromatographie mit porösem Protein A AgarosePerlen, die in Säulen verpackt sind, wohl die häufigste Methode zur Isolierung von Antikörpern und rekombinanten Proteinen im Labor maßstabsgetreu ist, die Fc-Fragmente von IgG exdrücken, kann es ein zeitaufwändiger und teurer Prozess sein. Zeit- und Finanzzwänge sind besonders beängstigend in kleinen wissenschaftlichen Grundlagenlabors, die Hunderte von Mikrogramm bis Milligramm Proteinmengen aus verdünnten Lösungen zurückgewinnen müssen, aber keinen Zugang zu Hochdruck-Flüssigkeitsabgabesystemen und/oder Personal mit Expertise in Bioseparationen haben. Darüber hinaus kann die Produktquantifizierung und -charakterisierung auch die Bearbeitungszeit über mehrere Arbeitstage hinaus übermäßig verlängern und die Ausgaben (Verbrauchsmaterialien, Löhne usw.)aufblähen. Daher ist ein schnelles, kostengünstiges und dennoch effektives Protokoll für die Isolierung und Charakterisierung von Antikörpern und anderen Proteinen, die ein Fc-Fragment besitzen, erforderlich. Zu diesem Zweck haben wir ein Protokoll entwickelt, das von technischem Personal mit begrenzter Erfahrung in weniger als 9 Stunden (ungefähr einen Arbeitstag) und bis zu 4 Stunden abgeschlossen werden kann, im Gegensatz zu herkömmlichen Methoden, die mehr als 20 Arbeitsstunden erfordern. Die meisten benötigten Geräte sind in standardbiomedizinischen, biochemischen und (bio-)chemischen Engineering-Labors leicht verfügbar, und alle Reagenzien sind im Handel erhältlich. Um dieses Protokoll zu demonstrieren, werden repräsentative Ergebnisse präsentiert, in denen chimäres murinisches Galant-1 mit dem menschlichen Fc (Gal-1hFc) aus Zellkulturüberstand verschmolzen wurde, mit einem Protein-A-Membranadsorber isoliert wurde. Gereinigte Gal-1hFc wurde mit einem beschleunigten Western Blotting-Analyseverfahren quantifiziert und mit Durchflusszytometrie charakterisiert. Der optimierte Workflow kann für andere Fc-exzessiven Proteine, wie Antikörper, geändert und/oder geändert werden, um alternative Quantifizierungs- und Charakterisierungsmethoden zu integrieren.

Das gestraffte Protokoll zur Isolierung und Charakterisierung von Fc-exezierenden Proteinen wird routinemäßig verwendet, um charisch-murines Galectin-1 mit dem menschlichen Fc (Gal-1hFc) aus verdünnten Zellkultur-Übertreibmitteln zu verarbeiten. Das Flussdiagramm in Abbildung 2 veranschaulicht den Workflow und die Zeit für jeden Schritt im Protokoll. Bei einer typischen Charge von 300 ml Überstand beträgt die Gesamtverarbeitungszeit ca. 9 Stunden, wenn die optionale Durchflusszytometrieprüfung vo...

Watch this Scientific Journal Video about Isolation and Characterization Of Chimeric Human Fc-expressing Proteins Using Protein A Membrane Adsorbers And A Streamlined Workflow at JoVE.com

Isolation and Characterization Of Chimeric Human Fc-expressing Proteins Using Protein A Membrane Adsorbers And A Streamlined Workflow

Im Vergleich zur traditionellen Affinitätschromatographie mit Protein A Agarose Perlen-verpackten Säulen können Protein-A-Membranadsorber die Isolation von Antikörpern und anderen Fc-Fragment-exemittierenden Proteinen im Labormaßstab erheblich beschleunigen. Geeignete Analyse- und Quantifizierungsmethoden können die Proteinverarbeitung weiter beschleunigen, so dass die Isolierung/Charakterisierung an einem Werktag statt an mehr als 20 Arbeitsstunden abgeschlossen werden kann.

Isolation und Charakterisierung von chimeric Human Fc-expressing Proteins Using Protein A Membrane Adsorbers And A Streamlined Workflow

Laboratory scale to industrial scale purification of biomolecules from cell culture supernatants and lysed cell solutions can be accomplished using ...

isolation-characterization-chimeric-human-fc-expressing-proteins

Research

JoVE Journal

Bioengineering

7.1K Aufrufe.  Ohio University. Im Vergleich zur traditionellen Affinitätschromatographie mit Protein A Agarose Perlen-verpackten Säulen können Protein-A-Membranadsorber die Isolation von Antikörpern und anderen Fc-Fragment-exemittierenden Proteinen im Labormaßstab erheblich beschleunigen. Geeignete Analyse- und Quantifizierungsmethoden können die Proteinverarbeitung weiter beschleunigen, so dass die Isolierung/Charakterisierung an einem Werktag statt an mehr als 20 Arbeitsstunden abgeschlossen w...

Serie: Isolation and Characterization Of Chimeric Human Fc-expressing Proteins Using Protein A Membrane Adsorbers And A Streamlined Workflow

Creating Two-Dimensional Patterned Substrates for Protein and Cell Confinement

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1 While microcontact printing can be employed to directly print a large number of molecules, including proteins,2 DNA,3 and silanes,4 the formation of self-assembled monolayers (SAMs) from long chain alkane thiols on gold provides a simple way to confine proteins and cells to specific patterns containing adhesive and resistant regions. This confinement can be used to control cell morphology and is useful for examining a variety of questions in protein and cell biology. Here, we describe a general method for the creation of well-defined protein patterns for cellular studies.5 This process involves three steps: the production of a patterned master using photolithography, the creation of a PDMS stamp, and microcontact printing of a gold-coated substrate. Once patterned, these cell culture substrates are capable of confining proteins and/or cells (primary cells or cell lines) to the pattern.
The use of self-assembled monolayer chemistry allows for precise control over the patterned protein/cell adhesive regions and non-adhesive regions; this cannot be achieved using direct protein stamping. Hexadecanethiol, the long chain alkane thiol used in the microcontact printing step, produces a hydrophobic surface that readily adsorbs protein from solution. The glycol-terminated thiol, used for backfilling the non-printed regions of the substrate, creates a monolayer that is resistant to protein adsorption and therefore cell growth.6 These thiol monomers produce highly structured monolayers that precisely define regions of the substrate that can support protein adsorption and cell growth. As a result, these substrates are useful for a wide variety of applications from the study of intercellular behavior7 to the creation of microelectronics.8
While other types of monolayer chemistry have been used for cell culture studies, including work from our group using trichlorosilanes to create patterns directly on glass substrates,9 patterned monolayers formed from alkane thiols on gold are straight-forward to prepare. Moreover, the monomers used for monolayer preparation are commercially available, stable, and do not require storage or handling under inert atmosphere. Patterned substrates prepared from alkane thiols can also be recycled and reused several times, maintaining cell confinement.10

Self-assembled monolayers (SAMs) formed from long chain alkane thiols on gold provide well-defined substrates for the formation of protein patterns and cell confinement. Microcontact printing of hexadecanethiol using a polydimethylsiloxane (PDMS) stamp followed by backfilling with a glycol-terminated alkane thiol monomer produces a pattern where protein and cells adsorb only to the stamped hexadecanethiol region.

Erstellen Zweidimensionale Patterned Substrate für Protein-und Zell-Confinement

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1  While microcontact printing ...

Forschung

Biotechnik

Detection and Isolation of Circulating Melanoma Cells using Photoacoustic Flowmetry

Circulating tumor cells (CTCs) are those cells that have separated from a macroscopic tumor and spread through the blood and lymph systems to seed secondary tumors1,2,3. CTCs are indicators of metastatic disease and their detection in blood samples may be used to diagnose cancer and monitor a patient&prime;s response to therapy. Since CTCs are rare, comprising about one tumor cell among billions of normal blood cells in advanced cancer patients, their detection and enumeration is a difficult task. We exploit the presence of pigment in most melanoma cells to generate photoacoustic, or laser induced ultrasonic waves in a custom flow cytometer for detection of circulating melanoma cells (CMCs)4,5. This process entails separating a whole blood sample using centrifugation and obtaining the white blood cell layer. If present in whole blood, CMCs will separate with the white blood cells due to similar density. These cells are resuspended in phosphate buffered saline (PBS) and introduced into the flowmeter. Rather than a continuous flow of the blood cell suspension, we induced two phase flow in order to capture these cells for further study. In two phase flow, two immiscible liquids in a microfluidic system meet at a junction and form alternating slugs of liquid6,7. PBS suspended white blood cells and air form microliter slugs that are sequentially irradiated with laser light. The addition of a surfactant to the liquid phase allows uniform slug formation and the user can create different sized slugs by altering the flow rates of the two phases. Slugs of air and slugs of PBS with white blood cells contain no light absorbers and hence, do not produce photoacoustic waves. However, slugs of white blood cells that contain even single CMCs absorb laser light and produce high frequency acoustic waves. These slugs that generate photoacoustic waves are sequestered and collected for cytochemical staining for verification of CMCs.

We have developed a flow cytometer using laser induced ultrasound to detect circulating melanoma cells as an early indicator of metastatic disease.

Erkennung und Isolierung von zirkulierenden Melanomzellen mit Photoakustische Flowmetrie

Circulating tumor cells (CTCs) are those cells that have separated from a macroscopic tumor and spread through the blood and lymph systems to seed ...

Membrane-SPINE: A Biochemical Tool to Identify Protein-protein Interactions of Membrane Proteins In Vivo

Membrane proteins are essential for cell viability and are therefore important therapeutic targets1-3. Since they function in complexes4, methods to identify and characterize their interactions are necessary5. To this end, we developed the Membrane Strep-protein interaction experiment, called Membrane-SPINE6. This technique combines in vivo cross-linking using the reversible cross-linker formaldehyde with affinity purification of a Strep-tagged membrane bait protein. During the procedure, cross-linked prey proteins are co-purified with the membrane bait protein and subsequently separated by boiling. Hence, two major tasks can be executed when analyzing protein-protein interactions (PPIs) of membrane proteins using Membrane-SPINE: first, the confirmation of a proposed interaction partner by immunoblotting, and second, the identification of new interaction partners by mass spectrometry analysis. Moreover, even low affinity, transient PPIs are detectable by this technique. Finally, Membrane-SPINE is adaptable to almost any cell type, making it applicable as a powerful screening tool to identify PPIs of membrane proteins.

Membrane-SPINE: A Biochemical Tool to Identify Protein-protein Interactions of Membrane Proteins In Vivo

A biochemical approach is described to identify in vivo protein-protein interactions (PPI) of membrane proteins. The method combines protein cross-linking, affinity purification and mass spectrometry, and is adaptable to almost any cell type or organism. With this approach, even the identification of transient PPIs becomes possible.

Membran-DORN: Ein Tool, um biochemische Protein-Protein-Interaktionen von Membranproteinen Identifizieren<em&gt; In Vivo</em

Membrane proteins are essential for cell viability and are therefore important therapeutic targets1-3. Since they function in complexes4, methods to ...

Synthesis of an Intein-mediated Artificial Protein Hydrogel

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of this hydrogel are two protein block-copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. A highly hydrophilic random coil is inserted into one of the block-copolymers for water retention. Mixing of the two protein block copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit with crosslinkers at either end that rapidly self-assembles into a hydrogel. This hydrogel is very stable under both acidic and basic conditions, at temperatures up to 50 &#176;C, and in organic solvents. The hydrogel rapidly reforms after shear-induced rupture. Incorporation of a &#34;docking station peptide&#34; into the hydrogel building block enables convenient incorporation of &#34;docking protein&#34;-tagged target proteins. The hydrogel is compatible with tissue culture growth media, supports the diffusion of 20 kDa molecules, and enables the immobilization of bioactive globular proteins. The application of the intein-mediated protein hydrogel as an organic-solvent-compatible biocatalyst was demonstrated by encapsulating the horseradish peroxidase enzyme and corroborating its activity.

We present the synthesis of a split-intein-mediated protein hydrogel. The building blocks of this hydrogel are two protein copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. Mixing of the two protein copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit that self-assembles into a hydrogel. This hydrogel is highly pH- and temperature-stable, compatible with organic solvents, and easily incorporates functional globular proteins.

Synthese einer Intein-vermittelten Protein-Hydrogel Künstliche

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of ...

Characterization of Complex Systems Using the Design of Experiments Approach: Transient Protein Expression in Tobacco as a Case Study

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the additional advantage of short development and production times, but expression levels can vary significantly between batches thus giving rise to regulatory concerns in the context of good manufacturing practice. We used a design of experiments (DoE) approach to determine the impact of major factors such as regulatory elements in the expression construct, plant growth and development parameters, and the incubation conditions during expression, on the variability of expression between batches. We tested plants expressing a model anti-HIV monoclonal antibody (2G12) and a fluorescent marker protein (DsRed). We discuss the rationale for selecting certain properties of the model and identify its potential limitations. The general approach can easily be transferred to other problems because the principles of the model are broadly applicable: knowledge-based parameter selection, complexity reduction by splitting the initial problem into smaller modules, software-guided setup of optimal experiment combinations and step-wise design augmentation. Therefore, the methodology is not only useful for characterizing protein expression in plants but also for the investigation of other complex systems lacking a mechanistic description. The predictive equations describing the interconnectivity between parameters can be used to establish mechanistic models for other complex systems.

We describe a design of experiments approach that can be used to determine and model the influence of transgene regulatory elements, plant growth and development parameters, and incubation conditions on the transient expression of monoclonal antibodies and reporter proteins in plants.

Charakterisierung komplexer Systeme Mit dem Design of Experiments Ansatz: Transient Protein Expression in Tabak als Case Study

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the ...

Expression, Isolation, and Purification of Soluble and Insoluble Biotinylated Proteins for Nerve Tissue Regeneration

Recombinant protein engineering has utilized Escherichia coli (E. coli) expression systems for nearly 4 decades, and today E. coli is still the most widely used host organism. The flexibility of the system allows for the addition of moieties such as a biotin tag (for streptavidin interactions) and larger functional proteins like green fluorescent protein or cherry red protein. Also, the integration of unnatural amino acids like metal ion chelators, uniquely reactive functional groups, spectroscopic probes, and molecules imparting post-translational modifications has enabled better manipulation of protein properties and functionalities. As a result this technique creates customizable fusion proteins that offer significant utility for various fields of research. More specifically, the biotinylatable protein sequence has been incorporated into many target proteins because of the high affinity interaction between biotin with avidin and streptavidin. This addition has aided in enhancing detection and purification of tagged proteins as well as opening the way for secondary applications such as cell sorting. Thus, biotin-labeled molecules show an increasing and widespread influence in bioindustrial and biomedical fields. For the purpose of our research we have engineered recombinant biotinylated fusion proteins containing nerve growth factor (NGF) and semaphorin3A (Sema3A) functional regions. We have reported previously how these biotinylated fusion proteins, along with other active protein sequences, can be tethered to biomaterials for tissue engineering and regenerative purposes. This protocol outlines the basics of engineering biotinylatable proteins at the milligram scale, utilizing&#160; a T7 lac inducible vector and E. coli expression hosts, starting from transformation to scale-up and purification.

Developing biotinylatable fusion proteins has many potential applications in various fields of research. Recombinant protein engineering is a straight forward procedure that is cost-effective, providing high yields of custom-designed proteins.

Expression, Isolierung und Reinigung von löslichen und unlöslichen biotinylierter Proteine ​​für Nervengeweberegeneration

Recombinant protein engineering has utilized Escherichia coli (E. coli) expression systems for nearly 4 decades, and today E. coli is still the most ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range of 10-100 &#197;. By measuring the distances under various ligated conditions, conformational changes of the protein can be easily assessed. With LRET, a lanthanide, most often chelated terbium, is used as the donor fluorophore, affording advantages such as a longer donor-only emission lifetime, the flexibility to use multiple acceptor fluorophores, and the opportunity to detect sensitized acceptor emission as an easy way to measure energy transfer without the risk of also detecting donor-only signal. Here, we describe a method to use LRET on membrane proteins expressed and assayed on the surface of intact mammalian cells. We introduce a protease cleavage site between the LRET fluorophore pair. After obtaining the original LRET signal, cleavage at that site removes the specific LRET signal from the protein of interest allowing us to quantitatively subtract the background signal that remains after cleavage. This method allows for more physiologically relevant measurements to be made without the need for purification of protein.

We describe here an improved Luminescence Resonance Energy Transfer (LRET) method where we introduce a protease cleavage site between the donor and acceptor fluorophore sites. This modification allows us to obtain specific LRET signals arising from membrane proteins of interest, allowing for the study of membrane proteins without protein purification.

Lumineszenz-Resonanzenergietransfer zu Konformationsänderungen in Membranproteinen in Säugerzellen exprimiert Studieren

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.
A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.
This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett&#8217;s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

Herstellung, Charakterisierung und Einsatzmöglichkeiten von 3D-Tissue-Engineering Menschen Ösophagus-Schleimhaut-Modell

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore ...

Biomechanical Characterization of Human Soft Tissues Using Indentation and Tensile Testing

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should mimic the human tissues they are aiming to replace; to provide the required anatomical shape, the materials must be able to sustain the mechanical forces they will experience when implanted at the defect site. Although the mechanical properties of tissue-engineered scaffolds are of great importance, many human tissues that undergo restoration with engineered materials have not been fully biomechanically characterized. Several compressive and tensile protocols are reported for evaluating materials, but with large variability it is difficult to compare results between studies. Further complicating the studies is the often destructive nature of mechanical testing. Whilst an understanding of tissue failure is important, it is also important to have knowledge of the elastic and viscoelastic properties under more physiological loading conditions.
This report aims to provide a minimally destructive protocol to evaluate the compressive and tensile properties of human soft tissues. As examples of this technique, the tensile testing of skin and the compressive testing of cartilage are described. These protocols can also be directly applied to synthetic materials to ensure that the mechanical properties are similar to the native tissue. Protocols to assess the mechanical properties of human native tissue will allow a benchmark by which to create suitable tissue-engineered substitutes.

Tissue biomechanics is important for maintaining cell shape and function and for determining phenotype. This report demonstrates non-destructive mechanical protocols for characterizing elastic and viscoelastic properties of human soft tissues, which can be directly applied to tissue-engineered substrates to allow a close matching of engineered materials to native tissue.

Biomechanische Charakterisierung humaner Weichgewebeproben mit Einrückungen und Zugprüfung

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should ...

Fabrication and Characterization of Optical Tissue Phantoms Containing Macrostructure

The rapid development of new optical imaging techniques is dependent on the availability of low-cost, customizable, and easily reproducible standards. By replicating the imaging environment, costly animal experiments to validate a technique may be circumvented. Predicting and optimizing the performance of in vivo and ex vivo imaging techniques requires testing on samples that are optically similar to tissues of interest. Tissue-mimicking optical phantoms provide a standard for evaluation, characterization, or calibration of an optical system. Homogenous polymer optical tissue phantoms are widely used to mimic the optical properties of a specific tissue type within a narrow spectral range. Layered tissues, such as the epidermis and dermis, can be mimicked by simply stacking these homogenous slab phantoms. However, many in vivo imaging techniques are applied to more spatially complex tissue where three dimensional structures, such as blood vessels, airways, or tissue defects, can affect the performance of the imaging system. 
This protocol describes the fabrication of a tissue-mimicking phantom that incorporates three-dimensional structural complexity using material with optical properties of tissue. Look-up tables provide India ink and titanium dioxide recipes for optical absorption and scattering targets. Methods to characterize and tune the material optical properties are described. The phantom fabrication detailed in this article has an internal branching mock airway void; however, the technique can be broadly applied to other tissue or organ structures.

Optical tissue phantoms are essential tools for calibration and characterization of optical imaging systems and validation of theoretical models. This article details a method for phantom fabrication that includes replication of tissue optical properties and three-dimensional tissue structure.

Herstellung und Charakterisierung von optischen Gewebe Phantome, die Makrostruktur enthalten

The rapid development of new optical imaging techniques is dependent on the availability of low-cost, customizable, and easily reproducible standards. By ...