Microiodometric Determination of β-Lactamase Activity
AbstractMicroiodometric Determination of β-Lactamase Activity R. B. Sykes and K. Nordström 1 a Department of Bacteriology, The Medical School, University of Bristol, Bristol BS8 1TD, England ABSTRACT The product of β-lactamase activity (a penicilloic acid in the case of a penicillin) is stoichiometrically oxidized by iodine. Hence, the β-lactamase activity can be measured as decolorization of the blue starch-iodine complex. Since the decolorization is a slow process, the rate of decolorization gave an underestimate of the rate of penicillin hydrolysis until a steady state was obtained after 15 to 20 min. If the reaction mixture (3 ml) contained no more than 0.001 unit of enzyme, a correct determination of β-lactamase activity was obtained from the microiodometric method described. The method is sensitive and some applications are mentioned.