title: Specificities of extracellular and ribosomal serine proteinases from Bacillus natto, a food microorganism.
abstract: The specificities of extracellular and ribosomal serine proteinase from Bacillus natto, a food microorganism, were investigated. Both proteins have highly restricted and characteristic specificities. With the extracellular serine proteinase, initial cleavage site was observed at Leu15-Tyr16, secondary site at Ser9-His10 and additional cleavage sites at Gln4-His5 and His5-Leu6 in the oxidized insulin B-chain. Hydrolysis of proangiotensin with the extracellular serine proteinase was observed primarily at Phe8-His9 and secondary at Tyr4-Ile5. The extracellular serine proteinase has a Km of 0.08 mM and kcat of 3 S-1 for angiotensin hydrolysis. With the ribosomal proteinase, initial cleavage site of the oxidized insulin B-chain was observed at Leu15-Tyr16 and additional cleavage site at Phe24-Phe25. Hydrolysis of proangiotensin was observed at Tyr4-Ile5 bond with the ribosomal proteinase.
mesh_terms: D000808:Angiotensinogen / Q000378:metabolism; D001230:Aspergillus / Q000201:enzymology; D001407:Bacillus / Q000201:enzymology*; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D005110:Extracellular Space / Q000201:enzymology; D007328:Insulin / Q000378:metabolism; D012270:Ribosomes / Q000201:enzymology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D012697:Serine Endopeptidases; D013302:Streptomyces / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D007328:Insulin; D000808:Angiotensinogen; D010450:Endopeptidases; D012697:Serine Endopeptidases