Many diverse clinical isolates of (48 strains), (25), biogroup 2 (48) and biogroup 3 (21) from man were examined for their ability to produce proteolytic enzymes and the nature and characteristics of the proteases were studied. All the isolates, most (94-90%) of the and biogroup 2 isolates, but only 71% of the biogroup 3 isolates, secreted proteolytic enzymes. These were detected most readily at pH 8 with gelatin as substrate. A strong correlation was found between the ability of a strain to form swarming growth and its ability to secrete proteases. Non-swarming isolates invariably appeared to be non-proteolytic. However, some isolates, particularly of biogroup 3, were non-proteolytic even when they formed swarming growth. Analysis of the secreted enzymes of the different spp. on polyacrylamide-gelatin gels under various constraints of pH and other factors showed that they were all EDTA-sensitive metalloproteinases. Analysis of the kinetics of production of the proteases revealed the formation of an additional protease of undefined type and function that was cell-associated and formed before the others were secreted. The secreted protease was subsequently modified to two isoforms whose mass (53-46 kDa) varied with the spp. and the strain. There was no evidence that the secreted proteases of strains of spp. were of types other than metalloproteinases.


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