75] Bifunctional reagents

Abstract

This chapter discusses the mechanism and properties of various bifunctional reagents such as bifunctional maleimide derivatives, alkyl halides, aryl halides, and isocyanates. Three general types of product are considered in the reaction of proteins with bifunctional reagents, each product providing different ways of gathering information about the structure and function of proteins. The types of product and their potential uses are intramolecularly cross-linked proteins, homopolymers, and heteropolymers. The selection of the proper reagent must be determined primarily by the specific product desired. The characterization of the product requires the same procedures as the characterization of proteins modified with monofunctional reagents. Glutaric dialdehyde reagent is commercially available as a 25% aqueous solution and can be purified by recrystallization as the bisulfite addition compound. The synthesis of a number of bifunctional imidoesters is described and preliminary results on their reaction with proteins are available. Bifunctional acylating reagents include a wide variety of compounds of different dimensions and reactivities, with monofunctional analogs available for control experiments.