CYTOCHROME-OXIDASE (A3) HEME AND COPPER OBSERVED BY LOW-TEMPERATURE FOURIER-TRANSFORM INFRARED-SPECTROSCOPY OF THE CO COMPLEX
CYTOCHROME-OXIDASE (A3) HEME AND COPPER OBSERVED BY LOW-TEMPERATURE FOURIER-TRANSFORM INFRARED-SPECTROSCOPY OF THE CO COMPLEX
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DOI：
10.1073/pnas.78.1.234
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
ALTSCHULD, RA
中科院分区：
文献类型：
--
作者：
ALBEN, JO;MOH, PP;ALTSCHULD, RA
利用牛心线粒体细胞色素c氧化酶（ferrocytochrome c：oxygen oxidoreductase，EC 1.9.3.1）底物还原的一氧化碳与铁或铜结合，研究了α 3血红素-铜口袋在15 K和80 K下在黑暗和可见光下的结构相互作用.用傅里叶变换红外干涉仪在黑暗中测得CO的振动吸收峰位于1963 cm ~（-1），在1952 cm ~（-1）附近有小的吸收峰，这是由于α_3血红素-CO络合物引起的。这些消失在强可见光下，并由在2062 cm-1的主要吸收和在2043 cm-1由于Cu-CO的次要吸收所取代。在黑暗中的松弛是快速和定量的在210 K，但变得可忽略不计低于140 K。多重重叠表明线粒体中细胞色素氧化酶的结构异质性。Cu-CO络合物（vCO）与软体动物（vCO = 2062 cm ~（-1））和甲壳动物（vCO = 2043 cm ~（-1））的血蓝蛋白-CO络合物相似。细胞色素氧化酶2062 cm ~（-1）Cu-CO吸收在15 K时分裂为两条带.光谱数据的分析表明存在一个非常非极性的血红素-铜口袋，其中血红素-CO复合物是高度有序的，但其中的Cu-CO复合物是更灵活的，特别是在80 K以上。提出了这些结构在氧还原中的作用。
Carbon monoxide bound to iron or copper in substrate-reduced mitochondrial cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) from beef heart has been used to explore the structural interaction of the a3 heme-copper pocket at 15 K and 80 K in the dark and in the presence of visible light. The vibrational absorptions of CO measured by a Fourier transform infrared interferometer occur in the dark at 1963 cm-1, with small absorptions near 1952 cm-1, and are due to a3 heme--CO complexes. These disappear in strong visible light and are replaced by a major absorption at 2062 cm-1 and a minor one at 2043 cm-1 due to Cu--CO. Relaxation in the dark is rapid and quantitative at 210 K, but becomes negligible below 140 K. The multiple absorptions indicate structural heterogeneity of cytochrome oxidase in mitochondria. The Cu--CO absorptions (vCO) are similar to those in hemocyanin--CO complexes from molluscs (vCO - 2062 cm-1) and crustaceans (vCO = 2043 cm-1). The 2062 cm-1 Cu--CO absorption of cytochrome oxidase is split into two bands at 15 K. Analysis of spectral data suggest the presence of a very nonpolar heme--Cu pocket in which the heme-CO complex is highly ordered, but in which the Cu--CO complex is much more flexible, especially above 80 K. A function for these structures in oxygen reduction is proposed.