金属与牛心细胞色素c氧化酶的活性独立于多肽亚基III、VII、a和b。

Metals and activity of bovine heart cytochrome c oxidase are independent of polypeptide subunits III, VII, a, and b.

作者信息

Yewey G L, Caughey W S

机构信息

Department of Biochemistry, Colorado State University, Fort Collins 80523.

出版信息

Biochem Biophys Res Commun. 1987 Nov 13;148(3):1520-6. doi: 10.1016/s0006-291x(87)80304-2.

DOI:10.1016/s0006-291x(87)80304-2

PMID:2825690

Abstract

Bovine heart cytochrome c oxidase, depleted of polypeptide subunits by alkaline detergent treatment, was characterized with respect to metal content, optical spectral properties, and oxidase activity. Treatment with 1.0% Triton X-100 at pH 9.5 followed by anion-exchange chromatography caused removal of subunit III, subunit VII, and polypeptides a and b. The metal atom stoichiometries of the control and the polypeptide-depleted enzyme were in both cases 2.5Cu/2Fe/1Zn/1Mg with metal-to-protein ratios significantly greater in the latter. The treated enzyme exhibited a red shifted oxidized Soret maximum and bound carbon monoxide upon reduction. Activity was markedly decreased by the treatment but was restored to control levels by incubation with 0.3% Tween 80 at pH 6.0. Therefore, subunit III, subunit VII, polypeptide a, and polypeptide b do not contain Cu, Fe, Zn, or Mg and are not essential for reduction of O2 by ferrocytochrome c.

摘要

通过碱性去污剂处理去除多肽亚基的牛心细胞色素c氧化酶，在金属含量、光谱特性和氧化酶活性方面进行了表征。在pH 9.5下用1.0% Triton X-100处理，然后进行阴离子交换色谱，导致亚基III、亚基VII以及多肽a和b被去除。对照酶和去除多肽的酶的金属原子化学计量比在两种情况下均为2.5Cu/2Fe/1Zn/1Mg，后者的金属与蛋白质的比率明显更高。处理后的酶在氧化态时呈现红移的Soret最大值，还原时能结合一氧化碳。处理后活性显著降低，但通过在pH 6.0下与0.3%吐温80孵育可恢复到对照水平。因此，亚基III、亚基VII、多肽a和多肽b不含铜、铁、锌或镁，并且对于亚铁细胞色素c还原氧气不是必需的。