1s6v
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(New page: 200px<br /><applet load="1s6v" size="450" color="white" frame="true" align="right" spinBox="true" caption="1s6v, resolution 1.88Å" /> '''Structure of a cytoc...)
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Revision as of 00:02, 21 November 2007
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Structure of a cytochrome c peroxidase-cytochrome c site specific cross-link
Overview
A specific covalently cross-linked complex between redox partners yeast, cytochrome c peroxidase (CCP) and cytochrome c (cyt. c) has been made by, engineering cysteines into CCP and cyt. c that form an intermolecular, disulfide bond in high yield. The crystal structure of the cross-linked, complex has been solved to 1.88-A resolution and closely resembles the, structure of the noncovalent complex [Pellitier, H. & Kraut, J. (1992), Science 258, 1748-1755]. The higher resolution of the covalent complex has, enabled the location of ordered water molecules at the, peroxidase-cytochrome c interface that serve to bridge between the two, proteins by hydrogen bonding. As in the noncovalent complex, direct, electrostatic interactions between protein groups appear not to be, critical in complex formation. UV-visible spectroscopic and stopped-flow, studies indicate that CCP in the covalent complex reacts normally with, H(2)O(2) to give compound I. Stopped-flow kinetic studies also show that, intramolecular electron transfer between the cross-linked ferrocytochrome, c and the Trp-191 cation radical site in CCP compound I occurs fast and is, nearly complete within the dead time ( approximately 2 ms) of the, instrument. These results indicate that the structure of the covalent, complex closely mimics the physiological electron transfer complex. In, addition, single-turnover and steady-state experiments reveal that CCP, compound I in the covalent complex oxidizes exogenously added, ferrocytochrome c at a slow rate (t(1/2) approximately 2 min), indicating, that CCP does not have a second independent site for physiologically, relevant electron transfer.
About this Structure
1S6V is a Protein complex structure of sequences from Saccharomyces cerevisiae with IOD and HEM as ligands. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Full crystallographic information is available from OCA.
Reference
Crystal structure and characterization of a cytochrome c peroxidase-cytochrome c site-specific cross-link., Guo M, Bhaskar B, Li H, Barrows TP, Poulos TL, Proc Natl Acad Sci U S A. 2004 Apr 20;101(16):5940-5. Epub 2004 Apr 7. PMID:15071191
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