Tissue-Digesting Enzyme (Histase) of Streptococci

Abstract

1. An extracellular, proteolytic enzyme has been observed in more than 30 strains of beta type, aerobic and facultative hemolytic streptococci. 2. The enzyme is readily demonstrable in sterile filtrates of cooked meat cultures. 3. No gas or foul odor is produced. 4. It is partially inactivated by exposure to about 60°C. for 45 minutes or longer. 5. The enzyme manifests itself in cooked meat cultures after about 48 hours incubation at 37°C. The sterile filtrate from a 10 day old culture acts within 18 hours. 6. From 50 to 75 per cent of the meat in a tube of cooked meat medium may be digested in about 3 weeks at room temperature after 5 days initial growth at 37°C. 7. No correlation is found, in the cases studied, between hemolysis and proteolysis. 8. Streptococci not digesting beef tissue will not digest human tissue, and those which do digest beef tissue also digest human tissue. This conclusion applies only to the nine strains studied. 9. Ability to digest animal tissues does not necessarily imply ability to digest casein, coagulated beef serum or gelatin. 10. The disappearance of the meat from cooked meat cultures of hemolytic streptococci is quantitatively roughly paralleled by increase of formol-titrable substances in the fluid portion of the medium. 11. The enzyme resembles trypsin in its action. Streptococci from a variety of sources, bovine, human and otherwise have shown varying degrees of proteolytic activity. 12. The name histase is proposed for this enzyme.

EXTRACELLULAR ANTIGENS IN STEADY-STATE CULTURES OF THE HEMOLYTIC STREPTOCOCCUS: PRODUCTION OF PROTEINASE AT LOW pH

“…Identification of component "B" with the streptococcal proteinase described by Elliott. The properties described above for component "B"production at a low pH range, water insolubility, high isoelectric point, precipitability at low concentrations of ammonium sulfate-were similar to those described by Elliott (1945) for the streptococcal proteinase studied by him, which may, in turn, have been the same enzyme as that described by Frobisher (1926) and Seegal and Seegal (1936). The following experiments were done: (a) Enzymatic activity of preparations containing component "B":- Elliott (1947) had found that the proteinase caused clotting of casein in skimmed milk, in the presence of thioglycolic acid or similar reducing substance, and that the enzyme was irreversibly inactivated by iodoacetate.…”

A Proteolytic Enzyme Produced by Group a Streptococci With Special Reference to Its Effect on the Type-Specific M Antigen

“…Frobisher (16) showed that culture filtrates of certain strains of hemo-lytic streptococci grown in cooked-meat medium digested animal muscle, He attributed this action to an extmcellular proteolytic enzyme elaborated by the microorganisms. From the data given it is impossible to determine whether the streptococcal enzyme for which Frobisher proposed the name "histase" is the same as the proteinase described in the present report.…”

A Study of Micrococcus Zymogenes

“…As controls on -the formol titrations of cooked meat medium, two strains of Streptococcus pyogenes, one a histase producer and the other a non-histase producer (Frobisher, 1926) were inoculated into similar media at the same time. Neither of these strains is known to have any proteolytic effect on milk, gelatin, coagulated serum or egg-white.3…”

“…The proteolytic enzymes of these organisms and their relation to proteases produced by streptococci may be mentioned here. Frobisher (1926) described a tissue digesting enzyme (histase) produced by beta type hemolytic streptococci. Hstase was thought to resemble trypsin in its action, but the streptococci which produced it had no demonstrable action on gelatin, coagulated serum or egg white.…”