2qr2
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(New page: 200px<br /> <applet load="2qr2" size="450" color="white" frame="true" align="right" spinBox="true" caption="2qr2, resolution 2.45Å" /> '''HUMAN QUINONE REDUC...)
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Revision as of 21:28, 12 November 2007
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HUMAN QUINONE REDUCTASE TYPE 2, COMPLEX WITH MENADIONE
Overview
In mammals, two separate but homologous cytosolic quinone reductases have, been identified: NAD(P)H:quinone oxidoreductase type 1 (QR1) (EC 1.6.99.2), and quinone reductase type 2 (QR2). Although QR1 and QR2 are nearly 50%, identical in protein sequence, they display markedly different catalytic, properties and substrate specificities. We report here two crystal, structures of QR2: in its native form and bound to menadione (vitamin, K(3)), a physiological substrate. Phases were obtained by molecular, replacement, using our previously determined rat QR1 structure as the, search model. QR2 shares the overall fold of the major catalytic domain of, QR1, but lacks the smaller C-terminal domain. The FAD binding sites of QR1, and QR2 are very similar, but their hydride donor binding sites are, considerably different. Unexpectedly, we found that QR2 contains a, specific metal binding site, which is not present in QR1. Two histidine, nitrogens, one cysteine thiol, and a main chain carbonyl group are, involved in metal coordination. The metal binding site is, solvent-accessible, and is separated from the FAD cofactor by a distance, of about 13 A.
About this Structure
2QR2 is a Single protein structure of sequence from Homo sapiens with ZN, FAD and VK3 as ligands. Active as NAD(P)H dehydrogenase (quinone), with EC number 1.6.5.2 Full crystallographic information is available from OCA.
Reference
Crystal structure of human quinone reductase type 2, a metalloflavoprotein., Foster CE, Bianchet MA, Talalay P, Zhao Q, Amzel LM, Biochemistry. 1999 Aug 3;38(31):9881-6. PMID:10433694
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