1dbi

<table><tr><td colspan='2'>[[1dbi]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_sp._ak1 Bacillus sp. ak1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DBI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1DBI FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene></td></tr>

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== Publication Abstract from PubMed ==

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.

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<ref>PMID:10588904</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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*[[Proteinase|Proteinase]]

== References ==

<references/>

[[Category: Bacillus sp. ak1]]

[[Category: Baker, E N]]

[[Category: Baker, H M]]

[[Category: Daniel, R M]]

[[Category: Smith, C A]]

[[Category: Toogood, H S]]

[[Category: Hydrolase]]