哺乳动物细胞色素c氧化酶中两种低Em形式的细胞色素a3及其一氧化碳复合物的表征
Characterization of two low Em forms of cytochrome a3 and their carbon monoxide complexes in mammalian cytochrome c oxidase.
作者信息
Sidhu G S, Hendler R W
机构信息
Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
出版信息
Biophys J. 1990 Jun;57(6):1125-40. doi: 10.1016/S0006-3495(90)82633-3.
Evidence is presented for the existence of two forms of low-potential cytochrome a3. One appears to be similar to the low-spin form reported by Nicholls, P., and V. Hildebrandt (1978 Biochem. J. 173:65-72) and Wrigglesworth, J. M., J. Elsden, A. Chapman, N. Van der Water, and M. F. Grahn (1988. Biochim. Biophys. Acta. 936:452-464). It has a reduced Soret peak near 428 nm and a prominent alpha peak near 602 nm. This form is seen when the enzyme is either supplemented with lipoprotein or incorporated into a liposomal membrane, preexposed to a voltage greater than 400 mV for at least 30 min, and titrated in the presence of approximately 1 mM K3Fe(CN)6. The other form has a reduced Soret peak near 446 nm, and no prominent alpha peak. The 428-nm form has an Em near 175 mV and forms a CO complex with an Em near 225 mV. The 446-nm form has an Em near 200 mV and forms a CO complex with an Em near 335 mV.
有证据表明存在两种低电位细胞色素a3形式。一种似乎与Nicholls, P.和V. Hildebrandt（1978年，《生物化学杂志》173:65 - 72）以及Wrigglesworth, J. M., J. Elsden, A. Chapman, N. Van der Water和M. F. Grahn（1988年，《生物化学与生物物理学报》936:452 - 464）报道的低自旋形式相似。它在428 nm附近有一个还原的Soret峰，在602 nm附近有一个明显的α峰。当酶补充脂蛋白或掺入脂质体膜中，预先暴露于大于400 mV的电压下至少30分钟，并在约1 mM K3Fe(CN)6存在下进行滴定，就会出现这种形式。另一种形式在446 nm附近有一个还原的Soret峰，没有明显的α峰。428 nm形式的Em接近175 mV，形成的CO复合物的Em接近225 mV。446 nm形式的Em接近200 mV，形成的CO复合物的Em接近335 mV。
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