Waldmeyer B, Bechtold R, Bosshard H R, Poulos T L
J Biol Chem. 1982 Jun 10;257(11):6073-6.
A hypothetical model of the cytochrome c peroxidase.cytochrome c complex (Poulos, T. L., and Kraut, J. (1980) J. Biol. Chem. 255, 10322-10330) predicts charge interactions between aspartic acid residues of the peroxidase having a spatial distribution that is complementary to the distribution of essential and highly conserved residues of cytochrome c. In a first attempt to test this model, carboxyl groups of cytochrome c peroxidase have been modified with a water-soluble carbodiimide, either alone or in combination with a nucleophile. Modification led to the loss of up to 90% of the ferrocytochrome c peroxidase activity. At least 4-5 carboxyl groups out of a total of 48, but none of the heme carboxyls, were modified in a derivative with 14% residual activity. In the peroxidase.cytochrome c complex the rate of peroxidase inactivation is slowed and approximately 2 carboxyl groups are protected from chemical modification. In the presence of the carbodiimide, cytochrome c and peroxidase were cross-linked to form a covalent 1:1 complex and the linkage sites were preliminarily characterized. Cross-linking occurred to carboxyl groups of the NH2-terminal fragment 1-119 and of fragment 172-229. The four crucial aspartates of the hypothetical model are located in these same two sequence regions.
细胞色素C过氧化物酶-细胞色素C复合物的一个假设模型（普oulos，T.L.，和克劳特，J.（1980年）《生物化学杂志》255，10322 - 10330）预测，过氧化物酶中天冬氨酸残基之间存在电荷相互作用，其空间分布与细胞色素C中必需且高度保守的残基分布互补。在首次尝试测试该模型时，细胞色素C过氧化物酶的羧基已用一种水溶性碳二亚胺单独或与亲核试剂结合进行了修饰。修饰导致高达90%的亚铁细胞色素C过氧化物酶活性丧失。在具有14%残余活性的衍生物中，总共48个羧基中至少有4 - 5个被修饰，但血红素羧基均未被修饰。在过氧化物酶-细胞色素C复合物中，过氧化物酶失活的速率减慢，约有2个羧基受到化学修饰的保护。在碳二亚胺存在下，细胞色素C和过氧化物酶交联形成共价1:1复合物，并对连接位点进行了初步表征。交联发生在NH2末端片段1 - 119和片段172 - 229的羧基上。假设模型中的四个关键天冬氨酸位于这相同的两个序列区域。
