title: Purification and properties of serine protease from Halobacterium halobium.
abstract: Pure extracellular serine protease was isolated from the culture filtrate of Halobacterium halobium by bacitracin-Sepharose affinity chromatography. The enzyme activity was completely and irreversibly lost if the NaCl concentration fell below 2 M. The protease consists of one polypeptide chain with a molecular weight of 41,000. It is characteristically enriched in Asx and Glx content, whereas the level of basic amino acids in the enzyme molecule is unusually low. The protease shows a preference for leucine in the carboxylic side of the scissile bond of the substrate, cleaving the B-chain of oxidized bovine insulin only at the Leu15-Tyr16 bond and liberating p-nitroaniline from L-pyroglutamyl-L-alanyl-L-alanyl-L-leucine-p-nitroanilide.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D010450:Endopeptidases / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D006217:Halobacterium / Q000201:enzymology*; D008970:Molecular Weight; D012697:Serine Endopeptidases; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D012965:Sodium Chloride; D010450:Endopeptidases; D012697:Serine Endopeptidases