X-ray structure of Escherichia coli pyridoxine 5'-phosphate oxidase complexed with pyridoxal 5'-phosphate at 2.0 A resolution.
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Safo MK, Musayev FN, di Salvo ML, Schirch V
X-ray structure of Escherichia coli pyridoxine 5'-phosphate oxidase complexed with pyridoxal 5'-phosphate at 2.0 A resolution.
J Mol Biol. 2001 Jul 20;310(4):817-26.
- PubMed ID
- 11453690 [ View in PubMed]
- Abstract
Escherichia coli pyridoxine 5'-phosphate oxidase catalyzes the terminal step in the biosynthesis of pyridoxal 5'-phosphate by the FMN oxidation of pyridoxine 5'-phosphate forming FMNH(2) and H(2)O(2). Recent studies have shown that in addition to the active site, pyridoxine 5'-phosphate oxidase contains a non-catalytic site that binds pyridoxal 5'-phosphate tightly. The crystal structure of pyridoxine 5'-phosphate oxidase from E. coli with one or two molecules of pyridoxal 5'-phosphate bound to each monomer has been determined to 2.0 A resolution. One of the pyridoxal 5'-phosphate molecules is clearly bound at the active site with the aldehyde at C4' of pyridoxal 5'-phosphate near N5 of the bound FMN. A protein conformational change has occurred that partially closes the active site. The orientation of the bound pyridoxal 5'-phosphate suggests that the enzyme catalyzes a hydride ion transfer between C4' of pyridoxal 5'-phosphate and N5 of FMN. When the crystals are soaked with excess pyridoxal 5'-phosphate an additional molecule of this cofactor is also bound about 11 A from the active site. A possible tunnel exists between the two sites so that pyridoxal 5'-phosphate formed at the active site may transfer to the non-catalytic site without passing though the solvent.