Comparison of phosphonate transition state analogs for inducing catalytic antibodies and evaluation of key structural factors by an ab initio study

The relation between the structure of haptens and the esterolytic activitie s of antibodies was investigated. We synthesized two phenylalanine analogs, the negatively charged phosphonate derivative I and the neutral phosphonam idate derivative 2. Seventeen out of 41 monoclonal antibodies generated aga inst the hapten 1 hydrolyzed the relevant phenylalanine ester R-12. On the contrary, none of 27 monoclonal antibodies generated against the hapten 2 h ad catalytic activity. An ab initio study of the structural and electronic properties of the modeled haptens showed that the value of the negative ele ctrostatic potential around the phosphonyl oxygen was an important factor a ffecting the induction of esterolytic antibodies. (C) 1999 Elsevier Science Ltd. All rights reserved.