A rat monoclonal antibody that catalyses the hydrolysis of a nitrophenyl-beta-lactam

We report the first example of a monoclonal antibody-catalysed hydrolysis of a beta-lactam where the antibodies were generated by a simple transition-state analogue. A rat monoclonal antibody (1/91c/4d/26) generated by using an acyclic 4-nitrophenylphosphate immunogen catalysed the hydrolysis of corresponding 4-nitrophenyl carbonates but, more importantly, also catalysed the hydrolysis of N-(4-nitrophenyl)-azetidinone at pH 8 with k(cat)=8.7 x 10(-6)s(-1) and K(M)=35 microM. This is the first example of a rat monoclonal catalytic antibody.