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ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATEISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATE
Structural highlights
Function[GLMS_ECOLI] Catalyzes the first step in hexosamine metabolism, converting fructose-6P into glucosamine-6P using glutamine as a nitrogen source. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedGlucosamine 6-phosphate synthase converts fructose-6P into glucosamine-6P or glucose-6P depending on the presence or absence of glutamine. The isomerase activity is associated with a 40-kDa C-terminal domain, which has already been characterized crystallographically. Now the three-dimensional structures of the complexes with the reaction product glucose-6P and with the transition state analog 2-amino-2-deoxyglucitol-6P have been determined. Glucose-6P binds in a cyclic form whereas 2-amino-2-deoxyglucitol-6P is in an extended conformation. The information on ligand-protein interactions observed in the crystal structures together with the isotope exchange and site-directed mutagenesis data allow us to propose a mechanism of the isomerase activity of glucosamine-6P synthase. The sugar phosphate isomerization involves a ring opening step catalyzed by His504 and an enolization step with Glu488 catalyzing the hydrogen transfer from C1 to C2 of the substrate. The enediol intermediate is stabilized by a helix dipole and the epsilon-amino group of Lys603. Lys485 may play a role in deprotonating the hydroxyl O1 of the intermediate. The mechanism of sugar phosphate isomerization by glucosamine 6-phosphate synthase.,Teplyakov A, Obmolova G, Badet-Denisot MA, Badet B Protein Sci. 1999 Mar;8(3):596-602. PMID:10091662[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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