Grimes C J, Piszkiewicz D, Fleischer E B
Proc Natl Acad Sci U S A. 1974 Apr;71(4):1408-12. doi: 10.1073/pnas.71.4.1408.
Chromous ion reacts with ferricytochrome c to yield a one-to-one Cr(III)-ferrocytochrome c complex. This material, when hydrolyzed by trypsin and subjected to chromatographic procedures, yielded two fragments containing chromium. The amino-acid compositions and chemical characteristics of each of these fragments indicated that the chromium had crosslinked two segments of polypeptide chain; these were residues 40-53-Cr(III)-residues 61-72 and residues 40-53-Cr(III)-residues 61-73. Examination of a model of the ferricytochrome c molecule indicated that only two residues of the crosslinked peptides were sufficiently close to allow crosslinking to take place. These residues were tyrosine 67 and asparagine 52. Enzymatic hydrolysis of one of those fragments by aminopeptidase M supported this identification. The position of the chromic ion implies what is the path of electron transfer from the chromous ion to the ferric ion in this chemical reduction of cytochrome c, and suggests a possible path of electron transfer in biological oxidation-reduction reactions.
亚铬离子与高铁细胞色素c反应生成一对一的Cr(III)-亚铁细胞色素c复合物。该物质经胰蛋白酶水解并进行色谱分析后，产生了两个含铬片段。这些片段各自的氨基酸组成和化学特性表明，铬使多肽链的两个区段发生了交联；即残基40 - 53 - Cr(III) - 残基61 - 72和残基40 - 53 - Cr(III) - 残基61 - 73。对高铁细胞色素c分子模型的研究表明，只有交联肽的两个残基足够接近，才能够发生交联。这些残基是酪氨酸67和天冬酰胺52。氨肽酶M对其中一个片段的酶促水解证实了这一鉴定结果。铬离子的位置暗示了在细胞色素c的这种化学还原过程中，电子从亚铬离子转移到铁离子的途径，并提示了生物氧化还原反应中可能的电子转移途径。
