Kennel S J, Meyer T E, Kamen M D, Bartsch R G
Proc Natl Acad Sci U S A. 1972 Nov;69(11):3432-5. doi: 10.1073/pnas.69.11.3432.
Interpretations of data bearing on structures of cytochromes cc'-a class of variant c-type heme proteins from bacteria-in support of a diheme-bearing single chain as a basic structural unit, appear to be invalid in the light of recent studies. These reveal that nearly all members of this class exist as dimers that can be dissociated into, if they do not already exist as, monoheme-bearing monomers. The particular case of the Chromatium protein, held to be the source of a peptic-"core" peptide containing two covalently-bonded heme groups, has been re-examined by preparation of tryptic and chymotryptic peptides derived from the heme-bearing region of the protein, as well as by repetition of experiments on peptic digestion, with more rigorous purification of the resultant peptides than was previously done. It is shown that this protein can also be dissociated into identical subunits, bearing a single heme prosthetic group, and accounting essentially for all its heme content. Thus, the previous terminology-cytochromes cc'-based on supposition of heme group heterogeneity, is inconsistent with these findings and should be replaced by cytochromes c'.
有关细胞色素cc'（一类来自细菌的c型血红素变体蛋白）结构的数据解释，支持将含双血红素的单链作为基本结构单元，但根据最近的研究，这些解释似乎是无效的。这些研究表明，这类蛋白几乎所有成员都以二聚体形式存在，如果它们本来不是以含单血红素的单体形式存在，也可以解离成这种单体。嗜色菌蛋白曾被认为是一种含两个共价结合血红素基团的胃蛋白酶“核心”肽的来源，现在通过制备来自该蛋白含血红素区域的胰蛋白酶和胰凝乳蛋白酶肽段，并重复胃蛋白酶消化实验，对最终肽段进行比以前更严格的纯化，重新进行了研究。结果表明，这种蛋白也可以解离成相同的亚基，每个亚基带有一个血红素辅基，基本上占其所有血红素含量。因此，以前基于血红素基团异质性假设的术语“细胞色素cc'”与这些发现不一致，应该被“细胞色素c'”所取代。
