2bgj

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{{STRUCTURE_2bgj| PDB=2bgj | SCENE= }}
{{STRUCTURE_2bgj| PDB=2bgj | SCENE= }}
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'''X-RAY STRUCTURE OF THE FERREDOXIN-NADP(H) REDUCTASE FROM RHODOBACTER CAPSULATUS AT 2.1 ANGSTROMS'''
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===X-RAY STRUCTURE OF THE FERREDOXIN-NADP(H) REDUCTASE FROM RHODOBACTER CAPSULATUS AT 2.1 ANGSTROMS===
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==Overview==
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The photosynthetic bacterium Rhodobacter capsulatus contains a ferredoxin (flavodoxin)-NADP(H) oxidoreductase (FPR) that catalyzes electron transfer between NADP(H) and ferredoxin or flavodoxin. The structure of the enzyme, determined by X-ray crystallography, contains two domains harboring the FAD and NADP(H) binding sites, as is typical of the FPR structural family. The FAD molecule is in a hairpin conformation in which stacking interactions can be established between the dimethylisoalloxazine and adenine moieties. The midpoint redox potentials of the various transitions undergone by R. capsulatus FPR were similar to those reported for their counterparts involved in oxygenic photosynthesis, but its catalytic activity is orders of magnitude lower (1-2 s(-)(1) versus 200-500 s(-)(1)) as is true for most of its prokaryotic homologues. To identify the mechanistic basis for the slow turnover in the bacterial enzymes, we dissected the R. capsulatus FPR reaction into hydride transfer and electron transfer steps, and determined their rates using stopped-flow methods. Hydride exchange between the enzyme and NADP(H) occurred at 30-150 s(-)(1), indicating that this half-reaction does not limit FPR activity. In contrast, electron transfer to flavodoxin proceeds at 2.7 s(-)(1), in the range of steady-state catalysis. Flavodoxin semiquinone was a better electron acceptor for FPR than oxidized flavodoxin under both single turnover and steady-state conditions. The results indicate that one-electron reduction of oxidized flavodoxin limits the enzyme activity in vitro, and support the notion that flavodoxin oscillates between the semiquinone and fully reduced states when FPR operates in vivo.
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{{ABSTRACT_PUBMED_16128574}}
==About this Structure==
==About this Structure==
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[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
[[Category: Rhodobacter capsulatus]]
[[Category: Rhodobacter capsulatus]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 05:51:25 2008''

Revision as of 02:51, 28 July 2008

Image:2bgj.png

Template:STRUCTURE 2bgj

X-RAY STRUCTURE OF THE FERREDOXIN-NADP(H) REDUCTASE FROM RHODOBACTER CAPSULATUS AT 2.1 ANGSTROMS

Template:ABSTRACT PUBMED 16128574

About this Structure

2BGJ is a Single protein structure of sequence from Rhodobacter capsulatus. Full crystallographic information is available from OCA.

Reference

The ferredoxin-NADP(H) reductase from Rhodobacter capsulatus: molecular structure and catalytic mechanism., Nogues I, Perez-Dorado I, Frago S, Bittel C, Mayhew SG, Gomez-Moreno C, Hermoso JA, Medina M, Cortez N, Carrillo N, Biochemistry. 2005 Sep 6;44(35):11730-40. PMID:16128574

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