Selection of reactive active site residues by affinity labeling

3 Selection of reactive active site residues by affinity labeling 

The active sites of enzymes frequently contain residues whose side chains play an important role in catalysis particularly because their reactivity is exacerbated by the local environment. Affinity labeling by reagents designed to dock in the active site and that able to form a stable covalent bond with a reactive side chain has been used to extract active enzymes or abzymes from libraries. 

Aldol condensation reactions are catalyzed by amines and the active sites of many aldolases contain an essential lysine residue. Using a strategy of reactive immunization with a 1,3-diketone (18 in Fig. 5.8), Wagner et al. were able to generate antibodies with aldolase activity. These were shown to possess a highly reactive lysine residue in 

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