1KOK

Crystal Structure of Mesopone Cytochrome c Peroxidase (MpCcP)

Summary for 1KOK

• Entry DOI: 10.2210/pdb1kok/pdb
• Related: 2CYP
• Descriptor: Cytochrome c Peroxidase, FE(III)-(4-MESOPORPHYRINONE) (3 entities in total)
• Functional Keywords: bifunctional catalyst, proximal loop, trp191 cationic radical, mesoporphyrin, nitrite reducatse, cytochrome c peroxidase, cytochrome oxidase, oxidoreductase
• Biological source: Saccharomyces cerevisiae (baker's yeast)
• Cellular location: Mitochondrion matrix: P00431
• Total number of polymer chains: 1
• Total formula weight: 34207.76

Authors

Bhaskar, B.,Immoos, C.E.,Cohen, M.S.,Barrows, T.P.,Farmer, P.J.,Poulos, T.L. (deposition date: 2001-12-20, release date: 2002-10-02, Last modification date: 2024-04-03)

Primary citation

Immoos, C.E.,Bhaskar, B.,Cohen, M.S.,Barrows, T.P.,Farmer, P.J.,Poulos, T.L.
Mesopone cytochrome c peroxidase: functional model of heme oxygenated oxidases.
J.Inorg.Biochem., 91:635-643, 2002

PubMed Abstract: 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.

PubMed: 12237229
DOI: 10.1016/S0162-0134(02)00447-6

Experimental method

X-RAY DIFFRACTION (1.7 Å)