1qyb
From Proteopedia
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X-ray crystal structure of Desulfovibrio vulgaris rubrerythrin with zinc substituted into the [Fe(SCys)4] site and alternative diiron site structures
Overview
The X-ray crystal structure of recombinant Desulfovibrio vulgaris, rubrerythrin (Rbr) that was subjected to metal constitution first with, zinc and then iron, yielding ZnS(4)Rbr, is reported. A [Zn(SCys)(4)] site, with no iron and a diiron site with no appreciable zinc in ZnS(4)Rbr were, confirmed by analysis of the anomalous scattering data. Partial reduction, of the diiron site occurred during the synchrotron X-ray irradiation at 95, K, resulting in two different diiron site structures in the ZnS(4)Rbr, crystal. These two structures can be classified as containing mixed-valent, Fe1(III)(mu-OH(-))(mu-GluCO(2)(-))(2)Fe2(II) and, Fe1(II)(mu-GluCO(2)(-))(2)Fe2(III)-OH(-) cores. The data do not show any, evidence for alternative positions of the protein or solvent ligands. The, iron and ligand positions of the solvent-bridged site are close to those, of the diferric site in all-iron Rbr. The diiron site with only the two, carboxylato bridges differs by an approximately 2 A shift in the position, of Fe1, which changes from six- to four-coordination. The Fe1- - -Fe2, distance (3.6 A) in this latter site is significantly longer than that of, the site with the additional solvent bridge (3.4 A) but significantly, shorter than that previously reported for the diferrous site (4.0 A) in, all-iron Rbr. The apparent redox-induced movement of Fe1 at 95 K in the, ZnS(4)Rbr crystal implies an extremely low activation barrier, which is, consistent with the rapid (approximately 30 s(-1)) room temperature, turnover of the all-iron Rbr during its catalysis of two-electron, reduction of hydrogen peroxide. ZnS(4)Rbr does not show peroxidase, activity, presumably because the [Zn(SCys)(4)] site, unlike the, [Fe(SCys)(4)] site, cannot mediate electron transfer to the diiron site., One or both of the diiron site structures in the cryoreduced ZnS(4)Rbr, crystal are likely to represent that (those) of transient mixed-valent, diiron site(s) that must occur upon return of the diferric to the, diferrous oxidation level during peroxidase turnover.
About this Structure
1QYB is a Single protein structure of sequence from Desulfovibrio vulgaris with FE, ZN and SO4 as ligands. Full crystallographic information is available from OCA.
Reference
X-ray crystal structure of Desulfovibrio vulgaris rubrerythrin with zinc substituted into the [Fe(SCys)4] site and alternative diiron site structures., Jin S, Kurtz DM Jr, Liu ZJ, Rose J, Wang BC, Biochemistry. 2004 Mar 23;43(11):3204-13. PMID:15023070
Page seeded by OCA on Wed Nov 21 01:07:25 2007
