ENZYMATIC PROPERTIES OF A PHAGE-INDUCED LYSIN AFFECTING GROUP A STREPTOCOCCI

Doughty, C. C. (University of Illinois College of Medicine, Chicago) and James A. Hayashi. Enzymatic properties of a phage-induced lysin affecting group A streptococci. J. Bacteriol. 83:1058-1068. 1962.-Phage-induced lysis of group C streptococci releases into the medium a lysin which completely lyses group A streptococci. Partial purification of the lytic activity yields 47% of the original activity with a 17-fold purification. The activity was assayed by observing lysis of group A streptococci under standard conditions. The optimal pH range for lysis is from 6.0 to 6.7. A monovalent cation requirement satisfied by Na(+), K(+), or Li(+) is shown by the lysin. Lysis is stimulated by ethylenedi-aminetetraacetic acid (EDTA), chlortetracycline, streptomycin, and penicillin. It is inhibited by p-hydroxymercuribenzoate (pHMB), and the inhibition is reversed by cysteine. Other inhibitors include ristocetin A and specific antisera against the lysin. Isolated group A streptococcal cell walls are partially lysed by massive amounts of lysin. This partial lysis is not affected by EDTA, pHMB, chlortetracycline, streptomycin, or ristocetin A. It is concluded that the enzymatic process of lysis of isolated cell walls is not identical to the more complex process resulting in lysis of intact cells.