1x9h
From Proteopedia
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Crystal structure of phosphoglucose/phosphomannose isomerase from Pyrobaculum aerophilum in complex with fructose 6-phosphate
Overview
The crystal structure of a dual-specificity phosphoglucose/phosphomannose, isomerase from the crenarchaeon Pyrobaculum aerophilum (PaPGI/PMI) has, been determined in complex with glucose 6-phosphate at 1.16 A resolution, and with fructose 6-phosphate at 1.5 A resolution. Subsequent modeling of, mannose 6-phosphate (M6P) into the active site of the enzyme shows that, the PMI activity of this enzyme may be due to the additional space, imparted by a threonine. In PGIs from bacterial and eukaryotic sources, which cannot use M6P as a substrate, the equivalent residue is a, glutamine. The increased space may permit rotation of the C2-C3 bond in, M6P to facilitate abstraction of a proton from C2 by Glu203 and, after a, further C2-C3 rotation of the resulting cis-enediolate, re-donation of a, proton to C1 by the same residue. A proline residue (in place of a glycine, in PGI) may also promote PMI activity by positioning the C1-O1 region of, M6P. Thus, the PMI reaction in PaPGI/PMI probably uses a cis-enediol, mechanism of catalysis, and this activity appears to arise from a subtle, difference in the architecture of the enzyme, compared to bacterial and, eukaryotic PGIs.
About this Structure
1X9H is a Single protein structure of sequence from Pyrobaculum aerophilum with SO4, F6R and GOL as ligands. Full crystallographic information is available from OCA.
Reference
Structural basis for phosphomannose isomerase activity in phosphoglucose isomerase from Pyrobaculum aerophilum: a subtle difference between distantly related enzymes., Swan MK, Hansen T, Schonheit P, Davies C, Biochemistry. 2004 Nov 9;43(44):14088-95. PMID:15518558
Page seeded by OCA on Wed Nov 21 05:54:56 2007
