Protein Cross-Linking & Protein Modification

Protein Cross-Linkers

Protein cross-linking or bioconjugation is the process of creating covalent bonds between two or more molecules. Cross-linkers may be divided into two general categories, homobifunctional and heterobifunctional.

A variety of homobifunctional cross-linkers such as BSOCOES, DSS, DST, Sulfo DST, and DTSSP are available. Homobifunctional cross-linkers have two identical reactive ends and are used in one-step reactions.

Heterobifunctional cross-linkers have two different reactive ends and are used in two-step sequential reactions. Primary amine + sulfhydryl reactive heterobifunctional cross-linkers MBS, Sulfo MBS, GMBS, sulfo GMBS, EMCH and others are available. The primary amine + carboxyl reactive cross-linker EDC is also offered. 

Also available are a large selection of photoreactive cross-linkers including ABH, APG, NHS-ASA, Sulfo SAND, and many others. For additional information about protein cross-linkers download our free handbook.

Protein Modification

G-Biosciences provide several protein reduction and modification reagents. Reduce stable disulfide bonds in less than 5 minutes at room temperature with Protein-S-S-Reductant™. Several other reducing agents are also available including, β-mercaptoethanol, DTT, Immobilized Reductant, Ellman’s Reagent, and many others. 

The alkylation of protein thiol groups protects reduced thiols from forming, or reforming after reduction, disulfide bonds or bridges. A selection of alkylation reagents are offered including 4-Vinylpyridine and OneQuant™ Iodoacetamide.

Proteolytic mapping is an effective method for identifying interaction sites between two or more proteins or protein subunits. A variety of reagents to facilitate this technique are available including the arginine specific endopeptidase SG-Arginine-C™, the serine endopeptidase SG-Chymotrypsin™, the serine endopeptidase SG-Glutamic-C™, and the highly specific serine protease SG-Lysine-C™.  Also available is the chemically methylated, TPCK treated affinity purified Mass Spectrometry Grade Trypsin.  Our trypsin is available as bovine or porcine and unlike other trypsin preparations, our Mass Spectrometry Grade Trypsin is highly stable.  As a result, it can be stored for a long period of time without any loss of activity.

Site selective modification of amino acid side chains is an important tool for analyzing natural systems, creating novel therapeutic conjugates, and understanding protein function. These modifications may inhibit side chain interactions or modify the charge to create more favorable reaction conditions. A variety of amino acid side chain modifiers are available from G-Biosciences, some of these agents include: the derivatizing agent DNFB for free thiols or alkylating, citraconic anyhdride which reacts with primary amines and blocks them by creating and amide linkage and a terminal carboxylate, SATA which adds protected sulfhydryls to primary amines, Sulfo NHS which converts carboxyl groups to amine reactive sulfo NHS esters, and many more.

In addition to our protein cross-linking and protein modification reagents, a variety of accessories including SpinOUT™ Columns, Optimizer Buffer™, Tube-O-Reactor™, and Tube-O-DIALYZER™ are available to ensure researchers achieve optimal results.