Purification and Characterization of a New Metal Protease Which Hydrolyzes the Cyclic Decapeptide, Gramicidin S

概要

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We screened a strain which can produce a new protease. The strain, Lactobacillus sp. no. 1,was isolated from a natural environment as an organism which could utilize gramicidin S as a sole nitrogen source. This strain was proved to produce much protease because it formed a large halo on a plate containing casein, and the protease was purified using ion exchange column chromatography. The amino-terminal amino acid sequence of the hydrolyzed products by the cleavage of gramicidin S was determined by a protein sequencer, and sizes of those products were analyzed by a mass spectrometer. The protease could cleave two peptide bonds between L-Orn-L-Leu in gramicidin S. These cleavage sites were different from other reported cleavage sites of gramicidin S by protease. The molecular weight of the protease was 42,000 by SDS-polyacrylamide gel electrophoresis. The optimum pH and temperature for the enzyme activity were 5.5 and 45℃, respectively. The enzyme activity was inhibited by EDTA, but not by phenylmethylsulfonyl fluoride (PMSF). Because the reported protease that can hydrolyze gramicidin S was a serine protease and the cleavage site was different from that of this protease from Lactobacillus sp. no. 1,we concluded that this enzyme was a new type of metal protease which can cleave both linear and cyclic peptide substrates with a unique substrate specificity.
社団法人日本生物工学会の論文
1993-03-25