铜绿假单胞菌细胞色素氧化酶的一些磁性特性。
Some magnetic properties of Pseudomonas cytochrome oxidase.
作者信息
Walsh T A, Johnson M K, Greenwood C, Barber D, Springall J P, Thomson A J
出版信息
Biochem J. 1979 Jan 1;177(1):29-39. doi: 10.1042/bj1770029.
The magnetic properties of the haem groups of Pseudomonas cytochrome oxidase and its cyanide-bound derivatives were studied in both the oxidized and reduced states by means of m.c.d. (magnetic circular dichroism) at low temperatures. In addition, the oxidized forms of the enzyme were also investigated by e.p.r. (electron-paramagnetic-resonance) spectroscopy, and a parallel study, using both e.p.r. and m.c.d., was made on Pseudomonas cytochrome c-551 to aid spectral assignments. For ascorbate-reduced Pseudomonas cytochrome oxidase, the temperature-independence of those features in the m.c.d. spectrum corresponding to the haem c, and the temperature-dependence of those signals corresponding to the haem d1, showed the former to be low-spin and the latter to be high-spin (s = 2). However, addition of cyanide to the reduced enzyme gave a form of the protein that was completely low-spin. The e.p.r. and m.c.d. sectra of oxidized Pseudomonas cytochrome oxidase and its cyanide derivative were consistent with the haem c and d1 components being low-spin in both cases. Pseudomonas cytochrome c-551 was found to be low-spin in both its oxidized and reduced redox states.
利用低温下的磁圆二色性（m.c.d.）对铜绿假单胞菌细胞色素氧化酶及其氰化物结合衍生物的血红素基团在氧化态和还原态下的磁性进行了研究。此外，还通过电子顺磁共振（e.p.r.）光谱对该酶的氧化形式进行了研究，并对铜绿假单胞菌细胞色素c - 551同时使用e.p.r.和m.c.d.进行了平行研究，以辅助光谱归属。对于抗坏血酸还原的铜绿假单胞菌细胞色素氧化酶，m.c.d.光谱中对应于血红素c的那些特征的温度独立性以及对应于血红素d1的那些信号的温度依赖性，表明前者为低自旋，后者为高自旋（s = 2）。然而，向还原酶中添加氰化物得到了一种完全低自旋的蛋白质形式。氧化的铜绿假单胞菌细胞色素氧化酶及其氰化物衍生物的e.p.r.和m.c.d.光谱与两种情况下血红素c和d1组分均为低自旋一致。发现铜绿假单胞菌细胞色素c - 551在其氧化态和还原态下均为低自旋。
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