1ta4
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(New page: 200px<br /><applet load="1ta4" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ta4, resolution 2.28Å" /> '''Crystal Structure Of...)
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Revision as of 00:59, 21 November 2007
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Crystal Structure Of Aspartate-Semialdehyde Dehydrogenase From Haemophilus Influenzae with a Bound Arsenate
Overview
The reversible dephosphorylation of beta-aspartyl phosphate to, L-aspartate-beta-semialdehyde (ASA) in the aspartate biosynthetic pathway, is catalyzed by aspartate-beta-semialdehyde dehydrogenase (ASADH). The, phosphate that is present to activate the aspartate carboxyl group is held, in a separate and distinct binding site once removed and prior to its, release from the enzyme. This site had been shown to be selective for, tetrahedral oxyanions, with several competitive inhibitors and alternative, substrates previously identified for the reverse reaction. Structural, studies have now shown that the most potent oxyanion inhibitor (periodate), and a good alternative substrate (arsenate) each occupy the same catalytic, phosphate-binding site. However, a rotation of a threonine side chain, (Thr137) in the periodate complex disrupts an important hydrogen-bonding, interaction with an active-site glutamate (Glu243) that participates in, substrate orientation. This subtle change appears to be the difference, between a substrate and an inhibitor of this enzyme.
About this Structure
1TA4 is a Single protein structure of sequence from Haemophilus influenzae with ART as ligand. Active as Aspartate-semialdehyde dehydrogenase, with EC number 1.2.1.11 Full crystallographic information is available from OCA.
Reference
Structural basis for discrimination between oxyanion substrates or inhibitors in aspartate-beta-semialdehyde dehydrogenase., Faehnle CR, Blanco J, Viola RE, Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 2):2320-4. Epub, 2004 Nov 26. PMID:15583380
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