1ebe
From Proteopedia
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==Overview== | ==Overview== | ||
| - | BACKGROUND: Cytochrome c peroxidase from yeast is a soluble, haem-containing protein found in the mitochondrial electron transport, chain where it probably protects against toxic peroxides. The aim of this, study was to obtain a reliable structure for the doubly oxidized transient, intermediate (termed compound I) in the reaction of cytochrome c, peroxidase with hydrogen peroxide. This intermediate contains a semistable, free radical on Trp191, and an oxyferryl haem group. RESULTS: Compound I, was produced in crystals of yeast cytochrome c peroxidase by reacting the, crystalline enzyme with hydrogen peroxide in a flow cell. The reaction was, monitored by microspectrophotometry and Laue crystallography in separate, experiments. A nearly complete conversion to compound I was achieved, ... | + | BACKGROUND: Cytochrome c peroxidase from yeast is a soluble, haem-containing protein found in the mitochondrial electron transport, chain where it probably protects against toxic peroxides. The aim of this, study was to obtain a reliable structure for the doubly oxidized transient, intermediate (termed compound I) in the reaction of cytochrome c, peroxidase with hydrogen peroxide. This intermediate contains a semistable, free radical on Trp191, and an oxyferryl haem group. RESULTS: Compound I, was produced in crystals of yeast cytochrome c peroxidase by reacting the, crystalline enzyme with hydrogen peroxide in a flow cell. The reaction was, monitored by microspectrophotometry and Laue crystallography in separate, experiments. A nearly complete conversion to compound I was achieved, within two minutes of the addition of hydrogen peroxide, and the, concentration of the intermediate remained at similar levels for an, additional half an hour. The structure of the intermediate was determined, by Laue diffraction. The refined Laue structure for compound I shows clear, structural changes at the peroxide-binding site but no significant changes, at the radical site. The photographs were processed with a new software, package (LEAP), overcoming many of the former problems encountered in, extracting structural information from Laue exposures. CONCLUSIONS: The, geometry of the haem environment in this protein allows structural changes, to be extremely small, similar in magnitude to those observed for the, Fe2+/Fe3+ transition in cytochrome c. The results suggest that these, molecules have evolved to transfer electrons with a minimal need for, structural adjustment. |
==About this Structure== | ==About this Structure== | ||
| - | 1EBE is a | + | 1EBE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with HEM and O as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Structure known Active Sites: HEM and OXO. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1EBE OCA]. |
==Reference== | ==Reference== | ||
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[[Category: oxidoreductase (h2o2(a))]] | [[Category: oxidoreductase (h2o2(a))]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 13:09:14 2007'' |
Revision as of 11:03, 5 November 2007
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LAUE DIFFRACTION STUDY ON THE STRUCTURE OF CYTOCHROME C PEROXIDASE COMPOUND I
Overview
BACKGROUND: Cytochrome c peroxidase from yeast is a soluble, haem-containing protein found in the mitochondrial electron transport, chain where it probably protects against toxic peroxides. The aim of this, study was to obtain a reliable structure for the doubly oxidized transient, intermediate (termed compound I) in the reaction of cytochrome c, peroxidase with hydrogen peroxide. This intermediate contains a semistable, free radical on Trp191, and an oxyferryl haem group. RESULTS: Compound I, was produced in crystals of yeast cytochrome c peroxidase by reacting the, crystalline enzyme with hydrogen peroxide in a flow cell. The reaction was, monitored by microspectrophotometry and Laue crystallography in separate, experiments. A nearly complete conversion to compound I was achieved, within two minutes of the addition of hydrogen peroxide, and the, concentration of the intermediate remained at similar levels for an, additional half an hour. The structure of the intermediate was determined, by Laue diffraction. The refined Laue structure for compound I shows clear, structural changes at the peroxide-binding site but no significant changes, at the radical site. The photographs were processed with a new software, package (LEAP), overcoming many of the former problems encountered in, extracting structural information from Laue exposures. CONCLUSIONS: The, geometry of the haem environment in this protein allows structural changes, to be extremely small, similar in magnitude to those observed for the, Fe2+/Fe3+ transition in cytochrome c. The results suggest that these, molecules have evolved to transfer electrons with a minimal need for, structural adjustment.
About this Structure
1EBE is a Single protein structure of sequence from Saccharomyces cerevisiae with HEM and O as ligands. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Structure known Active Sites: HEM and OXO. Full crystallographic information is available from OCA.
Reference
Laue diffraction study on the structure of cytochrome c peroxidase compound I., Fulop V, Phizackerley RP, Soltis SM, Clifton IJ, Wakatsuki S, Erman J, Hajdu J, Edwards SL, Structure. 1994 Mar 15;2(3):201-8. PMID:8069633
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