ABSTRACT
A homogeneous metalloproteinase has been isolated with a 28% yield from the culture fluid of Bacillus mesentericus, strain B-313. The isolation procedure included chromatography on bacitracin-silochrome and gel filtration on Acrylex P-10 and Sephadex G-75. The enzyme has a molecular mass of 41,000 Da; its N-terminal sequence, which appears as A-A-T-T-G-T-G-T-T-L-K-G-K-T-V-S-L-N-I, is identical with that of the B. amyloliquefaciens enzyme. Like other metalloproteinases, the enzyme is inhibited by o-phenanthroline and EDTA, has an activity maximum at 55 degrees C and pH 6.5-7.2, is stable at pH 7.0-9.5 and at temperature below 45 degrees C for several hours, and is irreversibly inactivated in acid media. As can be judged from the kcat/Km ratio dependence on pH, two ionogenic groups with pKa of 7.4 and 6.2 are involved in the catalytic act, presumably the imidazol group of histidine and the carboxylic group. Within synthetic peptides the enzyme hydrolyzes the bonds formed by the amino group of hydrophobic amino acids, mostly of leucine residues.
