PROPERTIES AND FUNCTION OF THE 2 HEMES IN PSEUDOMONAS CYTOCHROME-C PEROXIDASE
PROPERTIES AND FUNCTION OF THE 2 HEMES IN PSEUDOMONAS CYTOCHROME-C PEROXIDASE
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DOI：
10.1016/0167-4838(83)90413-2
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
VANNGARD, T
中科院分区：
文献类型：
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作者：
ELLFOLK, N;RONNBERG, M;VANNGARD, T
测定了铜绿假单胞菌细胞色素c过氧化物酶（铁细胞色素c：过氧化氢氧化还原酶EC 1.11.1.5）的2c型血红素的氧化还原电位，并且差异很大，分别约为+320和-330mV。温度低于 77°C 时的 EPR 谱。 K 仅显示低自旋信号（gz 3.24 和 2.93），而室温下的光谱表明酶中存在 1 个高自旋血红素和 1 个低自旋血红素。 77°C 静止状态和半还原酶的光学吸收光谱。 K缺乏高自旋化合物的特征。血红素配体排列在从 298°C 冷却到 298°C 时发生变化。至 77 度。 K 伴随着自旋状态的变化。过氧化物酶的活性形式是半还原酶，其中 1 个血红素处于亚铁状态，另一个处于三价铁状态（低自旋低于 77°K，gz 2.84）。半还原酶与 H2O2 反应形成化合物 I，其血红素主要为三价铁 (gz 3.15) 和 Ferri1 态。化合物 I 的半衰期为数秒，可转化为明显具有三价铁结构的化合物 II，其特征在于 g 3.6 处的 EPR 峰，具有不寻常的温度和弛豫行为。快速冷冻实验表明，化合物 II 是在化合物 I 的 1 电子还原过程中形成的。两种化合物的形成速率与它们参与催化循环的概念一致。
The oxidation-reduction potentials of the 2 c-type hemes of P. aeruginosa cytochrome c peroxidase (ferrocytochrome c:hydrogen-peroxide oxidoreductase EC 1.11.1.5) were determined and are widely different, about +320 and -330 mV, respectively. The EPR spectrum at temperatures below 77.degree. K reveals only low-spin signals (gz 3.24 and 2.93), whereas optical spectra at room temperature indicate the presence of 1 high-spin and 1 low-spin heme in the enzyme. Optical absorption spectra of resting and half-reduced enzyme at 77.degree. K lack features of a high-spin compound. The heme ligand arrangement changes on cooling from 298.degree. to 77.degree. K with a concomitant change in the spin state. The active form of the peroxidase is the half-reduced enzyme, in which 1 heme is in the ferrous and the other in the ferric state (low-spin below 77.degree. K with gz 2.84). Reaction of the half-reduced enzyme with H2O2 forms Compound I with the hemes predominantly in the ferric (gz 3.15) and the ferryl states. Compound I has a half-life of several seconds and is converted into Compound II apparently having a ferric-ferric structure, characterized by an EPR peak at g 3.6 with unusual temperature and relaxation behavior. Rapid-freeze experiments showed that Compound II is formed in a 1-electron reduction of Compound I. The rates of formation of both compounds are consistent with the notion that they are involved in the catalytic cycle.