Purification and Properties of the Exopenicillinase from Staphylococcus Aureus.

Resistance of Staphylococcus aureu8 to benzylpenicillin in clinical practice is usually caused by the production by the bacteria of an inducible penicillinase (EC 3.5.2.6) (Barber, 1962). The penicillinase of induced exponentially growing cultures of S. aureu8 is partitioned between the cells and the culture medium, the exact distribution varying from strain to strain and depending on the growth medium and the phase of growth (Swallow & Sneath, 1962; Novick, 1962a, 1963). In the strains used in the experiments described below about 60% of the enzyme activity is cell-bound at the end of exponential growth. All attempts to produce a soluble form of the cellbound enzyme have failed so far. The enzyme is closely associated with some insoluble part of the bacterial cell, since the purest preparations are particulate (Saz, Lowery & Jackson, 1961; M. H. Richmond, unpublished work). No systematic attempts to purify the exocellular enzyme have been reported, although Eriksen & Hansen (1954) noted that, like the penicillinases of Bacillubs cereus 569 and 5/B (Kogut, Pollock & Tridgell, 1956; Pollock, Torriani & Tridgell, 1956), the exoenzyme is strongly adsorbed to sintered glass. The present paper describes a method for purification of the exocellular penicilhinase produced by S. aureus, together with a description of some properties of the purified enzyme. The staphylococcal exo-enzyme is distinct in its properties and amino acid composition from the exopenicillinases obtained from B. cereus 569 and 5/B (Kogut et al. 1956; Pollock et at. 1956) and from Bacillus subtilis 6346 and 749 (M. R. Pollock, unpublished work). METHODS AND MATERIALS