Enzymatic characterization of glycosidase antibodies raised against a chair transition state analog and the retained catalytic activity from the expressed single chain antibody fragments

Abstract

Catalytic antibodies with a glycosidase activity have been generated against a chair-like transition state analogue. Two monoclonal antibodies with the highest activity were selected for cloning and sequencing. Sequence analysis of the two antibodies showed four amino acids differences in the framework region. Such a difference resulted in 8-fold difference in catalytic activity with p-nitrophenyl-beta-D-glucopyranoside between the two antibodies. Several Asp and Glu residues were found in the complimentarity determining region and some of these residue(s) might form the catalytic core for the glycosidase. Cloned antibody genes were expressed as a single chain antibody fragment. The expressed proteins showed the retained glycosidase activities.