2bii: Difference between revisions

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CRYSTAL STRUCTURE OF NITRATE-REDUCING FRAGMENT OF ASSIMILATORY NITRATE REDUCTASE FROM PICHIA ANGUSTA

OverviewOverview

Nitrate assimilation in autotrophs provides most of the reduced nitrogen, on earth. In eukaryotes, reduction of nitrate to nitrite is catalyzed by, the molybdenum-containing NAD(P)H:nitrate reductase (NR; EC 1.7.1.1-3). In, addition to the molybdenum center, NR contains iron-heme and flavin, adenine dinucleotide as redox cofactors involved in an internal electron, transport chain from NAD(P)H to nitrate. Recombinant, catalytically active, Pichia angusta nitrate-reducing, molybdenum-containing fragment (NR-Mo), was expressed in P. pastoris and purified. Crystal structures for NR-Mo, were determined at 1.7 and 2.6 angstroms. These structures revealed a, unique slot for binding nitrate in the active site and identified key Arg, and Trp residues potentially involved in nitrate binding. Dimeric NR-Mo is, similar in overall structure to sulfite oxidases, with significant, differences in the active site. Sulfate bound in the active site caused, conformational changes, as compared with the unbound enzyme. Four ordered, water molecules located in close proximity to Mo define a nitrate binding, site, a penta-coordinated reaction intermediate, and product release., Because yeast NAD(P)H:NR is representative of the family of eukaryotic NR, we propose a general mechanism for nitrate reduction catalysis.

About this StructureAbout this Structure

2BII is a Single protein structure of sequence from Pichia angusta with SO4, NA, MTV and GOL as ligands. Active as Nitrate reductase (NAD(P)H), with EC number 1.7.1.2 Structure known Active Site: AC1. Full crystallographic information is available from OCA.

ReferenceReference

Structural basis of eukaryotic nitrate reduction: crystal structures of the nitrate reductase active site., Fischer K, Barbier GG, Hecht HJ, Mendel RR, Campbell WH, Schwarz G, Plant Cell. 2005 Apr;17(4):1167-79. Epub 2005 Mar 16. PMID:15772287

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	[[Category: oxidoreductase]]		[[Category: oxidoreductase]]

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