期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：11
页码：3432-3435
DOI：10.1073/pnas.69.11.3432
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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'.
