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spinqualitylabelsall models 1kok, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of Mesopone Cytochrome c Peroxidase (MpCcP)

Overview

The effect of heme ring oxygenation on enzyme structure and function has, been examined in a reconstituted cytochrome c peroxidase. Oxochlorin, derivatives were formed by OsO(4) treatment of mesoporphyrin followed by, acid-catalyzed pinacol rearrangement. The northern oxochlorin isomers were, isolated by chromatography, and the regio-isomers assignments determined, by 2D COSY and NOE 1H NMR. The major isomer, 4-mesoporphyrinone (Mp), was, metallated with FeCl(2) and reconstituted into cytochrome c peroxidase, (CcP) forming a hybrid green protein, MpCcP. The heme-altered enzyme has, 99% wild-type peroxidase activity with cytochrome c. EPR spectroscopy of, MpCcP intermediate compound I verifies the formation of the Trp(191), radical similar to wild-type CcP in the reaction cycle. Peroxidase, activity with small molecules is varied: guaiacol turnover increases, approximately five-fold while that with ferrocyanide is approximately 85%, of native. The electron-withdrawing oxo-substitutents on the cofactor, cause a approximately 60-mV increase in Fe(III)/Fe(II) reduction, potential. The present investigation represents the first structural, characterization of an oxochlorin protein with X-ray intensity data, collected to 1.70 A. Although a mixture of R- and S-mesopone isomers of, the FeMP cofactor was used during heme incorporation into the apo-protein, only the S-isomer is found in the crystallized protein.

About this Structure

1KOK is a Single protein structure of sequence from Saccharomyces cerevisiae with HIF as ligand. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Full crystallographic information is available from OCA.

Reference

Mesopone cytochrome c peroxidase: functional model of heme oxygenated oxidases., Immoos CE, Bhaskar B, Cohen MS, Barrows TP, Farmer PJ, Poulos TL, J Inorg Biochem. 2002 Sep 20;91(4):635-43. PMID:12237229

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