Bosshard H R, Snozzi M, Bachofen R
J Bioenerg Biomembr. 1987 Aug;19(4):375-82. doi: 10.1007/BF00768540.
Mitochondrial cytochrome c (horse), which is a very efficient electron donor to bacterial photosynthetic reaction centers in vitro, binds to the reaction center of Rhodospirillum rubrum with an approximate dissociation constant of 0.3-0.5 microM at pH 8.2 and low ionic strength. The binding site for the reaction center is on the frontside of cytochrome c which is the side with the exposed heme edge, as revealed by differential chemical acetylation of lysines of free and reaction-center-bound cytochrome c. In contrast, bacterial cytochrome c2 was found previously to bind to the detergent-solubilized reaction center through its backside, i.e., the side opposite to the heme cleft [Rieder, R., Wiemken, V., Bachofen, R., and Bosshard, H. R. (1985). Biochem. Biophys. Res. Commun. 128, 120-126]. Binding of mitochondrial cytochrome c but not of mitochondrial cytochrome c2 is strongly inhibited by low concentrations of poly-L-lysine. The results are difficult to reconcile with the existence of an electron transfer site on the backside of cytochrome c2.
线粒体细胞色素c（马源）在体外是细菌光合反应中心非常有效的电子供体，在pH 8.2和低离子强度下，它与红螺菌的反应中心结合，解离常数约为0.3 - 0.5微摩尔。通过对游离的和与反应中心结合的细胞色素c的赖氨酸进行差异化学乙酰化发现，反应中心的结合位点在细胞色素c的正面，即血红素边缘暴露的一侧。相比之下，先前发现细菌细胞色素c2通过其背面，即与血红素裂隙相对的一侧，与去污剂增溶的反应中心结合[里德，R.，维姆肯，V.，巴赫芬，R.，和博斯哈德，H. R.（1985年）。生物化学与生物物理研究通讯128，120 - 126]。低浓度的聚-L-赖氨酸强烈抑制线粒体细胞色素c的结合，但不抑制线粒体细胞色素c2的结合。这些结果难以与细胞色素c2背面存在电子转移位点的观点相协调。
