title: Crystal structure of a protein proteinase inhibitor, Streptomyces subtilisin inhibitor, at 2.3 angstrom resolution.
abstract: The crystal structure of a protein proteinase inhibitor, Streptomyces subtilisin inhibitor which strongly inhibits bacterial alkaline proteinases, was determined at 2.3 angstrom resolution. The subunit (molecular weight, 11,485) of this dimeric molecule has a unique fold of polypeptide chain with a five-fold anti-parallel beta-sheet structure (about 21% of the 113 amino acid residues) and two small segments of alpha-helices (about 16%). The region around the apparent reactive site, Met(73)-Val(74), is held tight by a combination of various structural features. The conformation of this region seems to have close similarity to that found in substrate analogues of low molecular weight bound to subtilisin BPN'.
mesh_terms: D003461:Crystallography; D004791:Enzyme Inhibitors; D011487:Protein Conformation; D013302:Streptomyces; D013381:Subtilisins / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D013381:Subtilisins