1b93
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(New page: 200px<br /><applet load="1b93" size="450" color="white" frame="true" align="right" spinBox="true" caption="1b93, resolution 1.90Å" /> '''METHYLGLYOXAL SYNTHA...)
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Revision as of 09:21, 20 November 2007
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METHYLGLYOXAL SYNTHASE FROM ESCHERICHIA COLI
Overview
BACKGROUND: The reaction mechanism of methylglyoxal synthase (MGS) is, believed to be similar to that of triosephosphate isomerase (TIM). Both, enzymes utilise dihydroxyacetone phosphate (DHAP) to form an enediol(ate), phosphate intermediate as the first step of their reaction pathways., However, the second catalytic step in the MGS reaction pathway is, characterized by the elimination of phosphate and collapse of the, enediol(ate) to form methylglyoxal instead of reprotonation to form the, isomer glyceraldehyde 3-phosphate. RESULTS: The crystal structure of MGS, bound to formate and substoichiometric amounts of phosphate in the space, group P6522 has been determined at 1.9 A resolution. This structure shows, that the enzyme is a homohexamer composed of interacting five-stranded, beta/alpha proteins, rather than the hallmark alpha/beta barrel structure, of TIM. The conserved residues His19, Asp71, and His98 in each of the, three monomers in the asymmetric unit bind to a formate ion that is, present in the crystallization conditions. Differences in the three, monomers in the asymmetric unit are localized at the mouth of the active, site and can be ascribed to the presence or absence of a bound phosphate, ion. CONCLUSIONS: In agreement with site-directed mutagenesis and, mechanistic enzymology, the structure suggests that Asp71 acts as the, catalytic base. Further, Asp20 and Asp101 are involved in intersubunit, salt bridges. These salt bridges may provide a pathway for transmitting, allosteric information.
About this Structure
1B93 is a Single protein structure of sequence from Escherichia coli with PO4 and FMT as ligands. Active as Methylglyoxal synthase, with EC number 4.2.3.3 Full crystallographic information is available from OCA.
Reference
The crystal structure of methylglyoxal synthase from Escherichia coli., Saadat D, Harrison DH, Structure. 1999 Mar 15;7(3):309-17. PMID:10368300
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