Studies on Penicillinase

On alkaline hydrolysis, penicillins are converted into penicilloic acids (1). Penicillinase appears to bring about the same transformation, in which a carboxyl group of pK 4.7 is generated (2). Foster (3) allowed penicillinase to act on penicillin in bicarbonate buffer in the Warburg respirometer and observed the evolution of COZ. Since such a reaction can be followed simply and with considerable accuracy, and since enzyme reaction velocities within certain limits are proportional to enzyme concentration, it was believed that a rapid and accurate assay for penicillinase, free of the numerous difficulties and inaccuracies of bioassay methods, could be developed by the manometric method. It was further considered that should the CO2 be released in stoichiometric proportion to the amount of penicillin present a direct chemical method of assaying penicillin itself might be developed. Furthermore, such a method lends itself very readily to a study of the kinetics of the reaction.