Properties of the gamma haemolysin of Staphylococcus aureus 'Smith 5R'.

Purified gamma haemolysin of Staphylococcus aureus was characterized in relation to the alpha, beta and delta haemolysins. The sedimentation coefficient of the gamma lysin was 2-65, somewhat higher than the S20,w values of 1-4 for freshly purified alpha lysin and 1-8 for the beta lysin. The molecular weight of gamma lysin determined by gel filtration was 45000 daltons. The pI of gamma lysin was 6-0, while that of the alpha, beta and delta lysins ranged from 8-5 to 9-6. The amino acid analysis of gamma lysin was characterized by low levels of methionine and histidine. Methionine was, however, the N-terminus, which suggested that all of the amino acid might be involved in the N-terminal group. The gamma lysin was immunologically distinct from the alpha, beta and delta lysins by quantitative precipitin tests; in Ouchterlony agar gel diffusion tests, single lines of precipitation were observed which showed no evidence of cross-reactions amongst the four haemolysins. Gamma, beta and delta lysins had no affect in mice when injected at increasing doses ranging from 0 to 100 mug. The alpha lysin killed mice, the LD50 dose being 0-60 +/- 0-12 mug, or 27 to 34 mug/kg mouse tissue. Gamma lysin was, however, lethal for guinea pigs when 50 mug quantities were injected intracradially. Gamma lysin also lysed human leucocytes and destroyed C-6 (human lymphoblast) cells.