Silvestrini M C, Colosimo A, Brunori M, Antonini E
Biochem J. 1978 Feb 1;169(2):257-63. doi: 10.1042/bj1690257.
By enzymic digestion of the polysaccharide part of the covalent complex between cytochrome c and Sephadex G-200, a new water-soluble cytochrome c derivative is obtained (called cytochrome cr). Measurement of the free amino groups of this derivative indicates that on average the molar ratio between cytochrome c and polysaccharide is close to 1. Chemical determination of the sugar content gives a value of approx. 24000 for the molecular weight of cytochrome cr. On these bases the soluble cytochrome cr complex may be thought of as a folded protein to which a long polysaccharide tail is covalently bound. The functional behaviour of cytochrome cr is much more similar to that of the native molecule than to that of the insoluble complex (cytochrome ci). In particular the kinetics of the reaction of cytochrome cr and cytochrome cn (native) with ascorbate, ferrocyanide-ferricyanide, O2 and cytochrome c oxidase were investigated in considerable detail. The results of these experiments, together with the observation that the insoluble complex of cytochrome c is a very poor substrate of cytochrome c oxidase [Colosimo, Brunori & Antonini (1976) Biochem. J. 153, (657-661], indicate that hindrance effects constraining the approach between cytochrome cr and its oxidase are of greater importance than specific chemical modifications in determining the functional behavior of the protein.
通过对细胞色素c与葡聚糖凝胶G - 200之间共价复合物的多糖部分进行酶解，得到一种新的水溶性细胞色素c衍生物（称为细胞色素cr）。对该衍生物游离氨基的测定表明，细胞色素c与多糖之间的平均摩尔比接近1。对糖含量的化学测定得出细胞色素cr的分子量约为24000。基于这些数据，可溶性细胞色素cr复合物可被认为是一种折叠蛋白，一条长多糖尾巴与之共价结合。细胞色素cr的功能行为与天然分子的功能行为更为相似，而与不溶性复合物（细胞色素ci）的功能行为不同。特别详细地研究了细胞色素cr和细胞色素cn（天然的）与抗坏血酸、亚铁氰化物 - 铁氰化物、O2以及细胞色素c氧化酶反应的动力学。这些实验结果，连同细胞色素c的不溶性复合物是细胞色素c氧化酶的非常差的底物这一观察结果[科洛西莫、布鲁诺里和安东尼尼（1976年）《生物化学杂志》153卷，（657 - 661页）]，表明在决定蛋白质的功能行为方面，限制细胞色素cr与其氧化酶接近的阻碍作用比特定化学修饰更为重要。
