CHEMICAL SYNTHESIS OF CYTOCHROME C--EVOLUTION OF CYTOCHROME C

真核生物的细胞色素c是同源的， 氨基酸序列的约20%是氨基酸。 理解 自然选择这些氨基酸的原因将有助于 了解这种蛋白质的重要特性， 细胞呼吸 研究这一原因的一种方法是 用其他氨基酸替换单个不变氨基酸， 化学合成，并检查对 结构-功能-动力学 合成涉及两个主要问题 通过梅里菲尔德固相法测定细胞色素c，首先将两个 片段形成脱辅基细胞色素c和第二，立体化学特异性 血红素与脱辅基细胞色素c的共价连接。 中所述 前几年，第二个问题已经解决， 从线粒体中溶解细胞色素c合成酶。 我们现在 关注第一个。 Corradin和哈伯里已经证明血红素片段[65-Hse-内酯]（1-65） 和用CNBr处理马获得的脱辅基片段（66-104 如果血红素被还原， 甲硫氨酸80-S-血红素键。 我们之前的研究表明， 血红素片段ferro或ferro（1-25）H和脱辅基细胞色素c形成一个有效的 复杂. 由于我们在另一份报告中描述的研究表明， 亮氨酸32，蛋氨酸80-S-血红素铁键，可能还有色氨酸 59个参与耦合相互作用以稳定它们的原子 配位时，脱辅基片段[65-Hse-内酯]（1-65）和（66-104）可以形成一个 如果亚铁血红素片段（1-25）是 礼物 这样形成的复合物反过来又会促进以下反应： 脱辅基片段的高丝氨酸-内酯[65-Hse-内酯]（1-65）与 形成脱辅基细胞色素c的脱辅基片段（66-104）的α-NH 2-基团 [65-Hse]（1-104）。 事实上，我们已经达到了40%的效率。 产物与血红素片段（1-25）-H形成了一个有效的复合物。

Cytochrome c of eucaryotic species are homologous and contain invariant amino acides in some 20% of the amino acid sequence. Understanding of the reason on which these amino acids have been selected by nature would help to understand the important properties of this protein essential for cellular respiration. An approach to the study of this reason is to replace the individual invariant amino acids with other amino acids by chemical synthesis and examine the effect on the structure-function-dynamics. Two major problems are involved in synthesis of cytochrome c by the Merrifield solid phase method, first joining of two fragments to form apocytochrome c and second, stereochemically specific covalent attachment of heme to apocytochrome c. As described in the previous years, the second problem has been solved by finding and solubilizing cytochrome c synthetase from mitochondria. We are now concerned with the first. Corradin and Harbury have shown that heme fragment [65-Hse-lactone] (1-65) and apofragment (66-104) obtained by treatment with CNBr of horse cytochrome c can be rejoined if the heme is reduced to facilitate formation of the methionine 80-S-heme bond. Our previous studies have shown that heme fragment ferri or ferro (1-25)H and apocytochrome c form a productive complex. Since our studies described in another report have indicated that leucine 32, the methionine 80-S-heme iron bond and probably also tryptophan 59 are involved in coupled interactions to stablize their atomic coordinates, apofragments [65-Hse-lactone](1-65) and (66-104) may form an ordered complex through this coupling if ferro heme fragment (1-25) is present. The complex thus formed would in turn facilitate the reaction of the homoserine-lactone of apofragment [65-Hse-lactone](1-65) with the Alpha-NH2-group of apofragment (66-104) to form apocytochrome c [65-Hse](1-104). Indeed, we have attained this joining in 40% efficiency. The product formed a productive complex with heme fragment (1-25)-H.