ABSTRACT
The chemical modification of proteins has extensive use in proteomics in several different categories. Chemical proteomics could be described as the application of “classical” solution chemistry, such as the use of alkylating agents, isotope-coded affinity tags and fluorescent probes, in quantitative proteomics. Activity-based proteomics is a term that has been used to describe methods for the identification and measurement of enzymes in situ in cell and biological fluids. Activity-based proteomics appears to use the chemistry that was developed for the affinity labeling of enzymes and suicide enzyme inhibitors. Several approaches have been developed for the study of protease activity expression in cellular systems and subsequently for proteomics. One approach has promoted derivatives of diisopropylphosphorofluoridate (DFP), one of the earliest described inhibitors of serine proteases. Peptide halomethyl ketones, most notably tosyl-phenylalanylchloromethyl ketone (TPCK) and tosyl-lysylchloromethyl ketone (TLCK), react with classical serine protease by alkylation of a histidine residue.
