ATALYTIC ANTIBODIES AND COCAINE

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This grant application proposes the development of monoclonal antibodies which will catalyze the hydrolysis of cocaine to the non-psychoactive compound ecgonine methyl ester. It is based on reports that catalytic monoclonal antibodies with highly selective esterase-like activity have been obtained by immunizing mice with phosphonate analogs of carboxylic esters. The phosphonate structure mimics the transition state for ester hydrolysis. Thus the binding site of the antibody stabilizes the transition state and accelerates ester hydrolysis. A phosphonate analog of cocaine will be synthesized and coupled to protein. Mice will be immunized and hybridomas prepared. These hybridomas will be screened in an enzyme-linked immunosorbent assay for binding to an analog of the phosphonate hapten. Antibodies from positive hybridomas will be tested for their ability to catalyze the hydrolysis of [3H]-cocaine (phenyl labeled) to [3H]-benzoic acid which will be extracted and measured. Both the catalytic and selectivity aspects of the antibodies will be investigated. It is expected that success in this proposed pilot study will lead to a grant application to study in detail the factors in the immunogen affecting selectivity and catalytic rate and the effects of passive immunization of animals on cocaine pharmacokinetics and pharmacodynamics. Cocaine is viewed as an excellent model drug with which to test the overall feasibility of catalytic antibodies in drug of abuse research. As synthetic enzymes, they may be used to enhance understanding of the drug metabolism process. They offer a means of manipulate the rate of removal of drug from the body and study the effects of that rate on pharmacological activity. For example, catalytic antibodies may be used to investigate the pharmacodynamic effects of rapid depletion of cocaine and thus shed light on the factors surrounding acute tolerance and withdrawal. Immobilized catalytic antibodies could be used in model "artificial livers" for pharmacokinetic modeling experiments. Eventually the concept could be expanded to other drugs of abuse and other routes of reaction. In addition to their value in basic pharmacological studies, catalytic antibodies might eventually have potential for detoxification or perhaps could be applied in drug abuse treatment to deny reinforcement by blocking or mitigating the psychological effects of drug taking.