Este trabajo fue apoyado en parte por el Instituto de Investigación Van Andel y una beca de investigación de los Institutos Nacionales de Salud (CA181343) a SBR

Los autores no tienen nada que revelar.

La fiabilidad de los anticuerpos en aplicaciones de investigación biomédica es fundamental 46 , 47 . Esto es especialmente cierto en la bioquímica de la cromatina dada la posición de los anticuerpos como herramientas clave para la mayoría de las técnicas desarrolladas para caracterizar la abundancia y distribución de histonas PTMs. El protocolo presentado aquí detalla un oleoducto optimizado para el diseño, fabricación y uso de microarrays de péptidos...

El ADN genómico se empaqueta elegantemente dentro del núcleo de la célula eucariota con proteínas histonas para formar cromatina. La subunidad de repetición de la cromatina es el nucleosoma, que consiste en 147 pares de bases de ADN envueltas alrededor de un núcleo octameric de las proteínas histonas - H2A, H2B, H3 y H4 1 . La cromatina se organiza ampliamente en euchromatina libremente envasada y dominios de heterocromatina fuertemente envasados. El grado de compactación de la cromatina regula la medida en que las máquinas de proteínas pueden acceder al ADN subyacente para llevar a cabo procesos fundamentales basados ​​en el ADN, como la replicación, la transcripción y la reparación. Los reguladores clave de la accesibilidad del genoma en el contexto de la cromatina son PTMs en la cola no estructurada y los dominios centrales de las proteínas histonas 2 , 3 . Las PTM histonas funcionan directamente influyendo en la estructura de la cromatina 4 e indirectamenteH la contratación de proteínas lectoras y sus complejos macromoleculares asociados que tienen actividades de remodelación, enzimática y andamiaje de la cromatina 5 . Los estudios de la función PTM de las histonas durante las últimas dos décadas sugieren abrumadoramente que estas marcas juegan un papel clave en la regulación del destino celular, el desarrollo de organismos y la iniciación / progresión de la enfermedad. Impulsados ​​por los avances en espectrometría de masas basado en la tecnología proteómica, más de 20 único histone PTMs en más de 80 residuos distintos de histonas se han descubierto [ 6] . En particular, estas modificaciones a menudo se producen en combinaciones, y en consonancia con la hipótesis de &quot;código de histonas&quot;, numerosos estudios sugieren que las proteínas lectoras son dirigidas a regiones discretas de cromatina a través del reconocimiento de combinaciones específicas de histonas PTMs 7 , 8 , 9 . Un desafío clave para avanzar será la asignación de funciones al grDebido a la lista de histonas PTMs y para determinar cómo específicas combinaciones de histonas PTMs orquestar las funciones dinámicas asociadas con la cromatina. Los anticuerpos son los reactivos de la linterna para la detección de PTM histonas. Como tal, más de 1.000 histonas PTM anticuerpos específicos han sido comercialmente desarrollado para su uso en la investigación de la bioquímica de la cromatina. Con el rápido desarrollo de la tecnología de secuenciación de ADN de alto rendimiento, estos reactivos están siendo utilizados ampliamente por investigadores individuales y iniciativas epigenómicas a gran escala ( por ejemplo , ENCODE y BLUEPRINT) en ChIP-seq (inmunoprecipitación de cromatina junto con secuenciación de próxima generación ) De tuberías para generar de alta resolución mapas espaciales de histonas PTM distribución de todo el genoma 10 , 11 . Sin embargo, estudios recientes han demostrado que la especificidad de los anticuerpos PTM de las histonas puede ser altamente variable y que estos reactivos presentan<html> Las propiedades avorables tales como el reconocimiento de epítopos fuera de objetivo, la fuerte influencia positiva y negativa por PTMs vecinas y la dificultad para discriminar la orden de modificación en un residuo particular ( por ejemplo , mono-, di- o trimetil-lisina) 12 , 13 , 14 , 15 , 16 , 17 , 18 . Por lo tanto, es necesario un riguroso control de calidad de los reactivos de anticuerpos específicos de histonas PTM para interpretar con precisión los datos generados con estos valiosos reactivos. La tecnología de microarray permite la interrogación simultánea de miles de interacciones macromoleculares en un formato de alto rendimiento, reproducible y miniaturizado. Por esta razón, una variedad de plataformas de microarrays se han creado para analizar la proteína-ADN 19 ,20, la proteína-proteína 21 , y las interacciones proteína-péptido 22. De hecho, los microarrays de péptidos histona han surgido como una plataforma de descubrimiento informativo para la investigación de la bioquímica de la cromatina, permitiendo el perfilado de alto rendimiento de los escritores, borradores y lectores de histonas PTMs 15 , 23, 24, y también para el análisis de la especificidad del anticuerpo de histona 17, 25. más allá de su aplicación en la cromatina y la epigenética investigación, las matrices de péptidos de histona tienen utilidad potencial como una prueba de diagnóstico / pronóstico para el lupus eritematoso sistémico y otras enfermedades autoinmunes donde anti- Se generan autoanticuerpos de cromatina 26 , 27 . Aquí, describimos una tubería integrada que hemos desarrollado para diseñar, fabricar yPara generar perfiles de especificidad para anticuerpos que reconocen las histonas y sus PTMs. El pipeline es facilitado por ArrayNinja, una aplicación de código abierto de software interactivo que recientemente desarrollamos, que integra las etapas de diseño y análisis de los experimentos con microarrays [ 28] . ArrayNinja funciona mejor en Google Chrome. En resumen, se utiliza una impresora de microarrays de contacto robótico para depositar una biblioteca de péptidos de histona conjugados con biotina en posiciones definidas en portaobjetos de microscopio de vidrio revestidos con estreptavidina. Las matrices se pueden utilizar entonces en un formato de ensayo competitivo y paralelo para interrogar las interacciones anticuerpo-epítopo ( Figura 1 ). La biblioteca de péptidos consiste en cientos de péptidos sintéticos únicos que albergan PTMs (acetilación de lisina, metilación de lisina / arginina y fosforilación serina / treonina) solos y en combinaciones relevantes derivadas en gran medida de conjuntos de datos proteómicos. Métodos de síntesis y validación de péptidos<html> Se detallan en otra parte 23 . Los datos generados a partir de nuestros esfuerzos de detección de anticuerpos PTM de histonas en curso que utilizan esta plataforma de matriz se archivan en un recurso público de la web, la Base de datos de especificidad de anticuerpos de histonas (www.histoneantibodies.com). En particular, los microarrays de péptidos de histona fabricados con variaciones de este protocolo también se han utilizado ampliamente para caracterizar la actividad de los dominios de lectores de PTM de histonas 8 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 y más recientemente a histona de perfil Actividades de escritor y borrador de PTM 24 . /files/ftp_upload/55912/55912fig1.jpg &quot;/&gt; Figura 1: Representación de dibujos animados del procedimiento escalonado para la detección de anticuerpos en un microarray de péptidos histona. Los péptidos de histona biotinilados que albergan modificaciones postraduccionales definidas (círculos rojos y azules) se co-imprimen con biotina-fluoresceína sobre vidrio revestido con estreptavidina. Las interacciones positivas se visualizan como fluorescencia roja. <a href="http://ecsource.jove.com/files/ftp_upload/55912/55912fig1large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a>

<table border="0" cellpadding="0" cellspacing="0" width="746">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Printing Buffer</td>
			<td style="width:107px;">ArrayIt</td>
			<td style="width:105px;">PPB</td>
			<td style="width:281px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">BSA</td>
			<td style="width:107px;">Omnipure</td>
			<td align="right" style="width:105px;">2390</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Streptavidin-coated glass microscope slides</td>
			<td style="width:107px;">Greiner Bio-one</td>
			<td>439003-25</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">polypropylene 384 well plate</td>
			<td style="width:107px;">Greiner Bio-one</td>
			<td align="right" style="width:105px;">784201</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Biotin-fluorescein</td>
			<td style="width:107px;">Sigma</td>
			<td align="right" style="width:105px;">53608</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">contact microarray printer</td>
			<td style="width:107px;">Aushon</td>
			<td align="right" style="width:105px;">2470</td>
			<td style="width:281px;">Aushon 2470 Microarray Printer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">contact microarray printer</td>
			<td style="width:107px;">Gene Machines</td>
			<td style="width:105px;">OmniGrid 100</td>
			<td style="width:281px;">OmniGrid Microarray Printer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">PBS</td>
			<td style="width:107px;">Invitrogen</td>
			<td align="right" style="width:105px;">14190</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Blocking Buffer</td>
			<td style="width:107px;">ArrayIt</td>
			<td style="width:105px;">SBB</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Hydrophobic wax pen</td>
			<td style="width:107px;">Vector Labs</td>
			<td style="width:105px;">H-4000</td>
			<td>ImmEdge Hydrophobic Barrier PAP Pen</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Silicon Gasket</td>
			<td style="width:107px;">Grace Bio-labs</td>
			<td align="right" style="width:105px;">622511</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Hybridization Vessel</td>
			<td style="width:107px;">Thermo Scientific</td>
			<td align="right">267061</td>
			<td>or similar vessel</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Fluorescent-dye conjugated secondary antibody</td>
			<td style="width:107px;">Life Technologies</td>
			<td>A-21244</td>
			<td style="width:281px;">Alexa Fluor 647 (anti-rabbit)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Fluorescent-dye conjugated secondary antibody</td>
			<td style="width:107px;">Life Technologies</td>
			<td>A-21235</td>
			<td style="width:281px;">Alexa Fluor 647 (anti-mouse)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Wax Imprinter</td>
			<td style="width:107px;">ArrayIt</td>
			<td>MSI48</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Tween-20</td>
			<td style="width:107px;">Omnipure</td>
			<td align="right" style="width:105px;">9490</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Microarray Scanner</td>
			<td style="width:107px;">Innopsys</td>
			<td style="width:105px;">InnoScan 1100AL</td>
			<td>or equivalent microarray scanner</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">EipTitan Histone Peptide Microarray</td>
			<td style="width:107px;">Epicypher</td>
			<td align="right" style="width:105px;">112001</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">AbSurance Pro Histone Peptide Microarray</td>
			<td style="width:107px;">Millipore</td>
			<td align="right" style="width:105px;">16668</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">MODified Histone Peptide Array</td>
			<td style="width:107px;">Active Motif</td>
			<td align="right" style="width:105px;">13001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Histone Code Peptide Microarrays</td>
			<td style="width:107px;">JPT</td>
			<td style="width:105px;">His_MA_01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Wax</td>
			<td style="width:107px;">Royal Oak</td>
			<td style="width:105px;">GulfWax</td>
			<td>for wax imprinter</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Humidified Microarray Slide Hybridization Chamber</td>
			<td style="width:107px;">VWR</td>
			<td style="width:105px;">97000-284</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">High throughput microscope slide washing chamber</td>
			<td style="width:107px;">ArrayIt</td>
			<td style="width:105px;">HTW</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Microscope slide centrifuge</td>
			<td style="width:107px;">VWR</td>
			<td>93000-204</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Antibody 1</td>
			<td>Abcam</td>
			<td align="right" style="width:105px;">8898</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Antibody 2</td>
			<td style="width:107px;">Millipore</td>
			<td style="width:105px;">07-473</td>
			<td></td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:255px;">Biotinylated histone peptide</td>
			<td style="width:107px;">EpiCypher</td>
			<td>12-0001</td>
			<td style="width:281px;">Example peptide. Similar peptides with various modifications are available from several commercial sources.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">ImageMagick</td>
			<td style="width:107px;"></td>
			<td style="width:105px;"></td>
			<td>https://www.imagemagick.org/script/index.php</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">ArrayNinja</td>
			<td style="width:107px;"></td>
			<td style="width:105px;"></td>
			<td>https://rothbartlab.vai.org/tools/</td>
		</tr>
	</tbody>
</table>

analysis of histone antibody specificity with peptide microarrays

Las modificaciones postraduccionales (PTMs) en las proteínas histonas son ampliamente estudiadas por sus papeles en la regulación de la estructura de la cromatina y la expresión génica. La producción en masa y la distribución de anticuerpos específicos de histonas PTMs ha facilitado enormemente la investigación sobre estas marcas. Como los anticuerpos histónicos PTM son reactivos clave para muchas aplicaciones de bioquímica de la cromatina, es necesario un análisis riguroso de la especificidad del anticuerpo para una interpretación precisa de los datos y un progreso continuo en el campo. Este protocolo describe una tubería integrada para el diseño, fabricación y uso de microarrays peptídicos para perfilar la especificidad de los anticuerpos histona. Los aspectos de diseño y análisis de este procedimiento son facilitados por ArrayNinja, un paquete de software interactivo y de código abierto que recientemente desarrollamos para simplificar la personalización de los formatos de impresión en microarrays. Este gasoducto se ha utilizado para examinar un gran número de anticonceptivos de histonas PTM comercialmente disponibles y ampliamente utilizadosS, y los datos generados a partir de estos experimentos están disponibles gratuitamente a través de una base de datos en línea y en expansión Histone Antibody Specificity. Más allá de las histonas, la metodología general aquí descrita puede aplicarse ampliamente al análisis de anticuerpos específicos de PTM.

Este protocolo se ha utilizado para diseñar y fabricar una plataforma de microarrays de péptidos para el análisis de la especificidad de anticuerpos histona PTM. El array consulta una biblioteca de más de 300 características únicas de péptidos (20 - 40 residuos de longitud) que representan muchas de las combinaciones conocidas de PTMs que se encuentran en el núcleo y la variante de las proteínas histonas [ 38] . Este gasoducto ha sido un caballo de batall...

Watch this Scientific Journal Video about Analysis of Histone Antibody Specificity with Peptide Microarrays at JoVE.com

Analysis of Histone Antibody Specificity with Peptide Microarrays

Análisis de especificidad de anticuerpos histona con microarrays peptídicos

Este manuscrito describe métodos para aplicar la tecnología de microarrays de péptidos a la especificidad de perfiles de anticuerpos que reconocen las histonas y sus modificaciones post-traduccionales.

Post-translational modifications (PTMs) on histone proteins are widely studied for their roles in regulating chromatin structure and gene expression. The ...

analysis-of-histone-antibody-specificity-with-peptide-microarrays

Research

JoVE Journal

Biochemistry

39.8K vistas.  Van Andel Research Institute.  Este manuscrito describe métodos para aplicar la tecnología de microarrays de péptidos a la especificidad de perfiles de anticuerpos que reconocen las histonas y sus modificaciones post-traduccionales. 

Video: Analysis of Histone Antibody Specificity with Peptide Microarrays

Laboratory Scale Production and Purification of a Therapeutic Antibody

Ensuring the successful production of a therapeutic antibody begins early on in the development process. The first stage is vector expression of the antibody genes followed by stable transfection into a suitable cell line. The stable clones are subjected to screening in order to select those clones with desired production and growth characteristics. This is a critical albeit time-consuming step in the process. This protocol considers vector selection and sourcing of antibody sequences for the expression of a therapeutic antibody. The methods describe preparation of vector DNA for stable transfection of a suspension variant of human embryonic kidney 293 (HEK-293) cell line, using polyethylenimine (PEI). The cells are transfected as adherent cells in serum-containing media to maximize transfection efficiency, and afterwards adapted to serum-free conditions. Large scale production, setup as batch overgrow cultures is used to yield antibody protein that is purified by affinity chromatography using an automated fast protein liquid chromatography (FPLC) instrument. The antibody yields produced by this method can provide sufficient protein to begin initial characterization of the antibody. This may include in vitro assay development or physicochemical characterization to aid in the time-consuming task of clonal screening for lead candidates. This method can be transferable to the development of an expression system for the production of biosimilar antibodies.

This protocol describes the production of a therapeutic antibody in a mammalian expression system. The methods described include preparation of vector DNA, stable transfection and serum-free adaptation of a human embryonic kidney 293 cell line, set up of large scale cultures and purification using affinity chromatography.

Laboratorio de producción a gran escala y purificación de un anticuerpo terapéutico

Ensuring the successful production of a therapeutic antibody begins early on in the development process. The first stage is vector expression of the ...

Investigación

Bioquímica

Easy Manipulation of Architectures in Protein-based Hydrogels for Cell Culture Applications

Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field of 3D templates is rising due to the potential resemblance of those materials to the natural extracellular matrix. Protein-based hydrogels are particularly promising because they can easily be functionalized and can achieve defined structures with adjustable physicochemical properties. However, the production of macroporous 3D templates for cell culture applications using natural materials is often limited by their weaker mechanical properties compared to those of synthetic materials. Here, different methods were evaluated to produce macroporous bovine serum albumin (BSA)-based hydrogel systems, with adjustable pore sizes in the range of 10 to 70 &#181;m in radius. Furthermore, a method to generate channels in this protein-based material that are several hundred microns long was established. The different methods to produce pores, as well as the influence of pore size on material properties such as swelling ratio, pH, temperature stability, and enzymatic degradation behavior, were analyzed. Pore sizes were investigated in the native, swollen state of the hydrogels using confocal laser scanning microscopy. The feasibility for cell culture applications was evaluated using a cell-adhesive RGD peptide modification of the protein system and two model cell lines: human breast cancer cells (A549) and adenocarcinomic human alveolar basal epithelial cells (MCF7).

Different methods to manipulate three-dimensional architecture in protein-based hydrogels are evaluated here with respect to material properties. The macroporous networks are functionalized with a cell-adhesive peptide, and their feasibility in cell culture is evaluated using two different model cell lines.

Fácil manipulación de arquitecturas en Hidrogeles basados en proteínas para aplicaciones de la cultura de célula

Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field ...

Semi-automated Biopanning of Bacterial Display Libraries for Peptide Affinity Reagent Discovery and Analysis of Resulting Isolates

Biopanning bacterial display libraries is a proven technique for peptide affinity reagent discovery for recognition of both biotic and abiotic targets. Peptide affinity reagents can be used for similar applications to antibodies, including sensing and therapeutics, but are more robust and able to perform in more extreme environments. Specific enrichment of peptide capture agents to a protein target of interest is enhanced using semi-automated sorting methods which improve binding and wash steps and therefore decrease the occurrence of false positive binders. A semi-automated sorting method is described herein for use with a commercial automated magnetic-activated cell sorting device with an unconstrained bacterial display sorting library expressing random 15-mer peptides. With slight modifications, these methods are extendable to other automated devices, other sorting libraries, and other organisms. A primary goal of this work is to provide a comprehensive methodology and expound the thought process applied in analyzing and minimizing the resulting pool of candidates. These techniques include analysis of on-cell binding using fluorescence-activated cell sorting (FACS), to assess affinity and specificity during sorting and in comparing individual candidates, and the analysis of peptide sequences to identify trends and consensus sequences for understanding and potentially improving the affinity to and specificity for the target of interest.

Biopanning bacterial display libraries is a proven technique for discovery of peptide affinity reagents, a robust alternative to antibodies. The semi-automated sorting method herein has streamlined biopanning to decrease the occurrence of false positives. Here we illustrate the thought process and techniques applied in evaluating candidates and minimizing downstream analysis.

Biopanning semi-automatizado de bibliotecas de exhibición bacteriana péptido afinidad reactivo descubrimiento y análisis de los aislamientos que

Biopanning bacterial display libraries is a proven technique for peptide affinity reagent discovery for recognition of both biotic and abiotic targets. ...

The Determination of Protease Specificity in Mouse Tissue Extracts by MALDI-TOF Mass Spectrometry: Manipulating PH to Cause Specificity Changes

Proteases have several biological functions, including protein activation/inactivation and food digestion. Identifying protease specificity is important for revealing protease function. The method proposed in this study determines protease specificity by measuring the molecular weight of unique substrates using Matrix-assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) mass spectrometry. The substrates contain iminobiotin, while the cleaved site consists of amino acids, and the spacer consists of polyethylene glycol. The cleaved substrate will generate a unique molecular weight using a cleaved amino acid. One of the merits of this method is that it may be carried out in one pot using crude samples, and it is also suitable for assessing multiple samples. In this article, we describe a simple experimental method optimized with samples extracted from mouse lung tissue, including tissue extraction, placement of digestive substrates into samples, purification of digestive substrates under different pH conditions, and measurement of the substrates&#39; molecular weight using MALDI-TOF mass spectrometry. In summary, this technique allows for the identification of protease specificity in crude samples derived from tissue extracts using MALDI-TOF mass spectrometry, which may easily be scaled up for multiple sample processing.

Here, we present a protocol to determine protease specificity in crude mouse tissue extracts using MALDI-TOF spectrometry.

Los extractos de la determinación de la especificidad de la proteasa en el tejido de ratón por espectrometría de masas MALDI-TOF: manipulando PH para causar cambios de la especificidad

Proteases have several biological functions, including protein activation/inactivation and food digestion. Identifying protease specificity is important ...

Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays

The screening of kinase inhibitors is crucial for better understanding properties of a drug and for the identification of potentially new targets with clinical implications. Several methodologies have been reported to accomplish such screening. However, each has its own limitations (e.g., the screening of only ATP analogues, restriction to using purified kinase domains, significant costs associated with testing more than a few kinases at a time, and lack of flexibility in screening protein kinases with novel mutations). Here, a new protocol that overcomes some of these limitations and can be used for the unbiased screening of kinase inhibitors is presented. A strength of this method is its ability to compare the activity of kinase inhibitors across multiple proteins, either between different kinases or different variants of the same kinase. Self-assembled protein microarrays generated through the expression of protein kinases by a human-based in vitro transcription and translation system (IVTT) are employed. The proteins displayed on the microarray are active, allowing for measurement of the effects of kinase inhibitors. The following procedure describes the protocol steps in detail, from the microarray generation and screening to the data analysis.

A detailed protocol for the generation of self-assembled human protein microarrays for the screening of kinase inhibitors is presented.

Detección de inhibidores de la quinasa en microarrays de proteínas humanas autoensamblados

The screening of kinase inhibitors is crucial for better understanding properties of a drug and for the identification of potentially new targets with ...

Isolation of Histone from Sorghum Leaf Tissue for Top Down Mass Spectrometry Profiling of Potential Epigenetic Markers

Histones belong to a family of highly conserved proteins in eukaryotes. They pack DNA into nucleosomes as functional units of chromatin. Post-translational modifications (PTMs) of histones, which are highly dynamic and can be added or removed by enzymes, play critical roles in regulating gene expression. In plants, epigenetic factors, including histone PTMs, are related to their adaptive responses to the environment. Understanding the molecular mechanisms of epigenetic control can bring unprecedented opportunities for innovative bioengineering solutions. Herein, we describe a protocol to isolate the nuclei and purify histones from sorghum leaf tissue. The extracted histones can be analyzed in their intact forms by top-down mass spectrometry (MS) coupled with online reversed-phase (RP) liquid chromatography (LC). Combinations and stoichiometry of multiple PTMs on the same histone proteoform can be readily identified. In addition, histone tail clipping can be detected using the top-down LC-MS workflow, thus, yielding the global PTM profile of core histones (H4, H2A, H2B, H3). We have applied this protocol previously to profile histone PTMs from sorghum leaf tissue collected from a large-scale field study, aimed at identifying epigenetic markers of drought resistance. The protocol could potentially be adapted and optimized for chromatin immunoprecipitation-sequencing (ChIP-seq), or for studying histone PTMs in similar plants.

The protocol has been developed to effectively extract intact histones from sorghum leaf materials for profiling of histone post-translational modifications that can serve as potential epigenetic markers to aid engineering drought resistant crops.

Aislamiento de histone del tejido de la hoja de sorgo para la perfilación de espectrometría de masas de arriba hacia abajo de marcadores epigenéticos potenciales

Histones belong to a family of highly conserved proteins in eukaryotes. They pack DNA into nucleosomes as functional units of chromatin. ...

Rapid Determination of Antibody-Antigen Affinity by Mass Photometry

Measurements of the specificity and affinity of antigen-antibody interactions are critically important for medical and research applications. In this protocol, we describe the implementation of a new single-molecule technique, mass photometry (MP), for this purpose. MP is a label- and immobilization-free technique that detects and quantifies molecular masses and populations of antibodies and antigen-antibody complexes on a single-molecule level. MP analyzes the antigen-antibody sample within minutes, allowing for the precise determination of the binding affinity and simultaneously providing information on the stoichiometry and the oligomeric state of the proteins. This is a simple and straightforward technique that requires only picomole quantities of protein and no expensive consumables. The same procedure can be used to study protein-protein binding for proteins with a molecular mass larger than 50 kDa. For multivalent protein interactions, the affinities of multiple binding sites can be obtained in a single measurement. However, the single-molecule mode of measurement and the lack of labeling imposes some experimental limitations. This method gives the best results when applied to measurements of sub-micromolar interaction affinities, antigens with a molecular mass of 20 kDa or larger, and relatively pure protein samples. We also describe the procedure for performing the required fitting and calculation steps using basic data analysis software.

We describe a single-molecule approach to antigen-antibody affinity measurements using mass photometry (MP). The MP-based protocol is fast, accurate, uses a very small amount of material, and does not require protein modification.

Determinación rápida de la afinidad anticuerpos-antígenos por fotometría de masas

Measurements of the specificity and affinity of antigen-antibody interactions are critically important for medical and research applications. In this ...

Cell-Free Production of Proteoliposomes for Functional Analysis and Antibody Development Targeting Membrane Proteins

Membrane proteins play essential roles in a variety of cellular processes and perform vital functions. Membrane proteins are medically important in drug discovery because they are the targets of more than half of all drugs. An obstacle to conducting biochemical, biophysical, and structural studies of membrane proteins as well as antibody development has been the difficulty in producing large amounts of high-quality membrane protein with correct conformation and activity. Here we describe a &#8220;bilayer-dialysis method&#8221; using a wheat germ cell-free system, liposomes, and dialysis cups to efficiently synthesize membrane proteins and prepare purified proteoliposomes in a short time with a high success rate. Membrane proteins can be produced as much as in several milligrams, such as GPCRs, ion channels, transporters, and tetraspanins. This cell-free method contributes to reducing the time, cost and effort for preparing high-quality proteoliposomes, and provides suitable means for functional analysis of membrane proteins, drug targets screening, and antibody development.

This protocol describes an efficient cell-free method for production of high-quality proteoliposome by bilayer-dialysis method using wheat cell-free system and liposomes. This method provides suitable means for functional analysis of membrane proteins, drug targets screening, and antibody development.

Producción libre de células de proteoliposomas para análisis funcional y desarrollo de anticuerpos dirigidos a proteínas de membrana

Membrane proteins play essential roles in a variety of cellular processes and perform vital functions. Membrane proteins are medically important in drug ...

Cryo-EM and Single-Particle Analysis with Scipion

Cryo-electron microscopy has become one of the most important tools in biological research to reveal the structural information of macromolecules at near-atomic resolution. In single-particle analysis, the vitrified sample is imaged by an electron beam and the detectors at the end of the microscope column produce movies of that sample. These movies contain thousands of images of identical particles in random orientations. The data need to go through an image processing workflow with multiple steps to obtain the final 3D reconstructed volume. The goal of the image processing workflow is to identify the acquisition parameters to be able to reconstruct the specimen under study. Scipion provides all the tools to create this workflow using several image processing packages in an integrative framework, also allowing the traceability of the results. In this article the whole image processing workflow in Scipion is presented and discussed with data coming from a real test case, giving all the details necessary to go from the movies obtained by the microscope to a high resolution final 3D reconstruction. Also, the power of using consensus tools that allow combining methods, and confirming results along every step of the workflow, improving the accuracy of the obtained results, is discussed.

Single-particle analysis in cryo-electron microscopy is one of the main techniques used to determine the structure of biological ensembles at high resolution. Scipion provides the tools to create the whole pipeline to process the information acquired by the microscope and achieve a 3D reconstruction of the biological specimen.

Análisis crio-EM y de partículas individuales con Scipion

Cryo-electron microscopy has become one of the most important tools in biological research to reveal the structural information of macromolecules at ...

In Vitro Characterization of Histone Chaperones using Analytical, Pull-Down and Chaperoning Assays

Histone proteins associate with DNA to form the eukaryotic chromatin. The basic unit of chromatin is a nucleosome, made up of a histone octamer consisting of two copies of the core histones H2A, H2B, H3, and H4, wrapped around by the DNA. The octamer is composed of two copies of an H2A/H2B dimer and a single copy of an H3/H4 tetramer. The highly charged core histones are prone to non-specific interactions with several proteins in the cellular cytoplasm and the nucleus. Histone chaperones form a diverse class of proteins that shuttle histones from the cytoplasm into the nucleus and aid their deposition onto the DNA, thus assisting the nucleosome assembly process. Some histone chaperones are specific for either H2A/H2B or H3/H4, and some function as chaperones for both. This protocol describes how in vitro laboratory techniques such as pull-down assays, analytical size-exclusion chromatography, analytical ultra-centrifugation, and histone chaperoning assay could be used in tandem to confirm whether a given protein is functional as a histone chaperone.

In Vitro Characterization of Histone Chaperones using Analytical, Pull-Down and Chaperoning Assays

This protocol describes a battery of methods that includes analytical size-exclusion chromatography to study histone chaperone oligomerization and stability, pull-down assay to unravel histone chaperone-histone interactions, AUC to analyze the stoichiometry of the protein complexes, and histone chaperoning assay to functionally characterize a putative histone chaperone in vitro.

In vitro Caracterización de chaperonas de histonas mediante ensayos analíticos, pull-down y acompañantes

Histone proteins associate with DNA to form the eukaryotic chromatin. The basic unit of chromatin is a nucleosome, made up of a histone octamer consisting ...