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1dbi
From Proteopedia
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CRYSTAL STRUCTURE OF A THERMOSTABLE SERINE PROTEASE
Overview
Proteins of the subtilisin superfamily (subtilases) are widely distributed, through many living species, where they perform a variety of processing, functions. They are also used extensively in industry. In many of these, enzymes, bound calcium ions play a key role in protecting against, autolysis and thermal denaturation. We have determined the crystal, structure of a highly thermostable protease from Bacillus sp. Ak.1 that is, strongly stabilized by calcium. The crystal structure, determined at 1.8 A, resolution (R=0. 182, Rfree=0.247), reveals the presence of four bound, cations, three Ca(2+) and one Na(+). Two of the Ca(2+) binding sites, Ca-1, and Ca-2, correspond to sites also found in thermitase and the mesophilic, subtilisins. The third calcium ion, however, is at a novel site that is, created by two key amino acid substitutions near Ca-1, and has not been, observed in any other subtilase. This site, acting cooperatively with, Ca-1, appears to give substantially enhanced thermostability, compared, with thermitase. Comparisons with the mesophilic subtilisins also point to, the importance of aromatic clusters, reduced hydrophobic surface and, constrained N and C termini in enhancing the thermostability of thermitase, and Ak.1 protease. The Ak.1 protease also contains an unusual Cys-X-Cys, disulfide bridge that modifies the active site cleft geometry.
About this Structure
1DBI is a Single protein structure of sequence from Bacillus sp. with CA and NA as ligands. Full crystallographic information is available from OCA.
Reference
Calcium-mediated thermostability in the subtilisin superfamily: the crystal structure of Bacillus Ak.1 protease at 1.8 A resolution., Smith CA, Toogood HS, Baker HM, Daniel RM, Baker EN, J Mol Biol. 1999 Dec 10;294(4):1027-40. PMID:10588904
Page seeded by OCA on Tue Nov 20 13:08:23 2007
Categories: Bacillus sp. | Single protein | Baker, E.N. | Baker, H.M. | Daniel, R.M. | Smith, C.A. | Toogood, H.S. | CA | NA | Hydrolase
