Some Properties of Two Extracellular β-Lactamases from Bacillus cereus 569/H

Abstract

Selective ihactivation of [beta]-lactamase 1 by heat in a partly purified preparation containing both enzymes was accompanied by a small increase in the [beta]-lactamase II activity with no evidence that this was due to the formation of [beta]-lactamase-II from [beta]-lactamase 1. Attempts to convert crystalline [beta]-lactamase 1 into an enzyme with the activity of [beta]-lactamase II were unsuccessful. The relationship of p-lactamase II to the cell-bound [gamma]-penicillinase from B. cereus 569 and 569/H which has a higher solubility in (NH4)2SO4 solution than the exopenicillinase described by Kogut et al. (1956) and a higher relative activity against methicillin (Ron-Zenziper & Citri, 1963), is still not determined. Since the term cephalosporinase does not adequately indicate the nature of the hydrolysable substrates of the enzyme from B. cereus 569/H that shows activity against cephalosporin-C it was replaced by the term [beta]-lactamase II in this communication.