1mos
From Proteopedia
ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH 2-AMINO-2-DEOXYGLUCITOL 6-PHOSPHATE
Overview
Glucosamine 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.
About this Structure
1MOS is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Sat May 3 01:31:59 2008
