Catalytic antibodies by fluorescence screening

A series of eleven immunizations against transition-state analogs were carr ied out to improve the catalytic Properties of Ab 9D9, a catalytic antibody that catalyzes a fluorogenic retro-Diels-Alder reaction liberating nitroxy l. By a direct fluorescence assay of cell-culture supernatant, eight new hy bridoma cell lines producing catalytic antibodies for the reaction were rea dily identified among more than 14000 individual samples. Our results demon strate that early catalysis screening by fluorescence allows an efficient s urvey of large antibody libraries, and may lead to rapid and significant im provement in catalysis.