Purification and properties of a new type of protease produced by Microbacterium liquefaciens.

A bacterium, identified as Microbacterium liquefaciens MIM-CG-9535-I, was isolated from a soil sample taken from the industrial site of a gelatin manufacturer. A new type of protease, which restrictively decomposes gelatin at one or two positions, was purified from the bacterial culture. The molecular mass of the purified enzyme was 21 kDa by SDS-polyacrylamide gel electrophoresis. The purified enzyme specifically degraded the alpha-chain of gelatin with a molecular weight of 100 kDa into two peptides of 60 kDa and 40 kDa. Native collagen was not a substrate for the enzyme.