ESTEROLYTIC ANTIBODIES INDUCED TO HAPTENS WITH A 1,2-AMINO ALCOHOL FUNCTIONALITY

Three structurally related haptens 1-3 were designed and synthesized w ith the goal of generating antibodies for the hydrolysis of ester 4a a nd amide 4b. These haptens contain a 1,2-amino alcohol functionality w hich replaces the ester/amide moiety of the substrates. A number of ca talytic antibodies were generated, and the Michaelis-Menten kinetics c onstants of three representative catalytic antibodies induced to each of haptens 1-3 were determined. These catalytic antibodies accelerated the hydrolysis of ester 4a with k(cat)/k(un) = approximately 3 X 10(3 ), and their catalytic activities were effectively inhibited by the ad dition of their respective haptens. To evaluate the structural influen ces of the hapten on antibody binding and specificity as well as catal ytic activity, a total of 18 antibodies including the above catalytic antibodies and three representative noncatalytic antibodies from each group were selected, and their dissociation constants with their respe ctive haptens, amide 4b, and products were determined. The studies hav e shown that (1) the structural variations among the three haptens ind uce no significant changes in catalytic activity of antibodies while t hey slightly influence the antibody binding and specificity for the su bstrate and products and (2) a high probability (reaching nearly 50%) of finding catalytic activity among the monoclonal antibodies raised t o hapten 1 is found, suggesting that the induction of a charged comple mentary amino acid residue in close proximity to the reaction site may be important to generation of catalytic antibodies.