Cross Linkages in Protein Chemistry

Abstract

Publisher Summary This chapter provides an overview of scattered and diverse data on the ability of proteins to form cross linkages that connect molecules or micelles, thus leading to the formation of larger aggregates. Even a single cross linkage between two large molecules has the immediate result of combining them into a unit having a molecular weight equal to the sum of the molecular weights of the molecules involved; repeated cross linkages multiply the size of molecules that are already extremely large. The immediately observable results are reduced solubility or peptizability, increased resistance to hydrothermal influences, and reduced resilience or elasticity accompanied by darkening in color, and in extreme cases, brittleness. The presence of many reactive groups in protein molecules make them particularly susceptible to cross-linking reactions. Aldehydes can form a methylene bridge, or can react with amino groups linking protein molecules together with the formation of Schiff bases. Dicarboxylic and particularly disulfonic acids can form cross-linking bridges by reaction with amino groups. The chapter briefly describes some of the principal purposes that have stimulated industrial experimentation with reactions involving cross linkage of proteins. It also outlines the types of industrial problems handled by cross-linking reactions. Further, the chapter describes cross-linking processes indicated in the literature.