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7CCP

EFFECT OF ARGININE-48 REPLACEMENT ON THE REACTION BETWEEN CYTOCHROME C PEROXIDASE AND HYDROGEN PEROXIDE

7CCP の概要
エントリーDOI10.2210/pdb7ccp/pdb
関連するPDBエントリー1BEJ 1BEM 1BEQ 1BES 1CCP 1CPD 1CPE 1CPF 1CPG 2CCP 3CCP 4CCP 5CCP 6CCP
分子名称CYTOCHROME C PEROXIDASE, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
機能のキーワードoxidoreductase
由来する生物種Saccharomyces cerevisiae (baker's yeast)
細胞内の位置Mitochondrion matrix: P00431
タンパク質・核酸の鎖数1
化学式量合計34342.06
構造登録者
Wang, J.,Miller, M.A.,Kraut, J. (登録日: 1993-06-07, 公開日: 1993-10-31, 最終更新日: 2024-03-06)
主引用文献Vitello, L.B.,Erman, J.E.,Miller, M.A.,Wang, J.,Kraut, J.
Effect of arginine-48 replacement on the reaction between cytochrome c peroxidase and hydrogen peroxide.
Biochemistry, 32:9807-9818, 1993
Cited by
PubMed Abstract: The crystallographic structures of two cytochrome c peroxidase (CcP) mutants, CcP(R48L) and CcP(R48K), have been determined. In addition, the electronic absorption spectrum and the hydrogen peroxide reactivity of these two mutants have been determined between pH 4 and 8. Both the crystallographic structure and the electronic absorption spectrum of CcP(R48L) are consistent with exclusive pentacoordination of the heme iron between pH 4 and 6.5. At higher pH, CcP(R48L) forms an alkaline bis-imidazole form of CcP with the distal histidine coordinated to the heme iron. The apparent pKA for this transition is 7.5 in CcP(R48L). The observed pseudo-first-order rate constant for the reaction between CcP(R48L) and hydrogen peroxide saturates at high peroxide concentrations. The data are consistent with a rate-limiting oxygen-oxygen bond scission at high peroxide concentrations. The observed rate of the bond scission step ranges between 1000 and 1950 s-1, an estimated 2 orders of magnitude slower than for wild-type enzyme. The data suggest that the protonated form of His-52 increases the bond scission step by a factor of 2. The properties of the CcP(R48K) mutant are significantly different from those of CcP(R48L). The crystal structure of CcP(R48K) shows Lys-48 occupying the putative peroxide binding site. The electronic absorption spectrum indicates that CcP(R48K) is predominantly pentacoordinate at neutral pH but with detectable amounts of hexacoordinate forms. Two ionizable groups affect the electronic absorption spectrum of CcP(R48K). An apparent ionization near pH 4 produces an enzyme with increased hexacoordination, while an apparent pKA of 6.9 generates the alkaline bis-imidazole form. The peroxide reaction saturates at high peroxide concentrations for CcP(R48K) and is attributed to a conformational-gating mechanism. The maximum rate for the reaction between CcP(R48K) and hydrogen peroxide is probably limited by the movement of either Lys-48 or His-52. This rate is 200 and 290 s-1 in nitrate-containing buffers and phosphate buffers, respectively. Evidence is provided that Arg-48 in wild-type enzyme is responsible for nitrate binding in the heme pocket and for stabilizing CcP Compound I.
PubMed: 8396973
DOI: 10.1021/bi00088a036
主引用文献が同じPDBエントリー
実験手法
X-RAY DIFFRACTION (2.2 Å)
構造検証レポート
Validation report summary of 7ccp
検証レポート(詳細版)ダウンロードをダウンロード

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件を2024-11-20に公開中

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