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| [[Image:1dbi.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1dbi| PDB=1dbi | SCENE= }} | | {{STRUCTURE_1dbi| PDB=1dbi | SCENE= }} |
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| '''CRYSTAL STRUCTURE OF A THERMOSTABLE SERINE PROTEASE'''
| | ===CRYSTAL STRUCTURE OF A THERMOSTABLE SERINE PROTEASE=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10588904}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10588904 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10588904}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Toogood, H S.]] | | [[Category: Toogood, H S.]] |
| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:39:33 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 22:46:50 2008'' |
