A novel protein with alkaline phosphatase and protease inhibitor activities in Streptomyces hiroshimensis

A novel alkaline phosphatase (S-ALP) was found in the culture filtrate of Streptomyces hiroshimensis IFO 12785. Purification was achieved on Sephadex G-75 column, palmitoylated gauze column, and Superdex 75 HR column chromatographies. The molecular weight of S-ALP was estimated to be 14200 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The isoelectric point is 9.2. S-ALP had maximum enzyme activity at pH 9.5. S-ALP efficiently catalyzed both p-nitrophenyl phosphate and p-nitrophenyl phosphorylcholine substrates, particularly the latter. The N-terminal amino acid sequence (25 residues) of S-ALP was 60 to 72% identical to that of Streptomyces subtilisin inhibitor-like proteins. S-ALP exhibited trypsin inhibition in addition to a strong inhibition of subtilisin.