Structural organization in peptide fragments of cytochrome c by heme binding

Xinshan Kang, Jannette Carey

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Prosthetic groups are often important structural organizers of proteins as well as essential functional components. Insertion of prosthetic groups is usually spontaneous, and implies an apoprotein that is partially preorganized to provide a recognition surface for specific binding. Cytochrome c is distinguished by having its heme attached by a dedicated heme lyase through thioether links to cysteine side-chains, and the apoprotein shows no evidence of preorganization under physiological conditions. Nevertheless, addition of heme to two short fragments of cytochrome c enhances helical structure substantially (from ~ 8% to ~ 22%), an effect that depends on iron ligation but not thioether linkage. The helical segments in the corresponding parts of the native holoprotein have little contact surface with heme, implying that the increased helical structure in the fragment complex may depend on tertiary interactions. The absence of the intervening polypeptide chain suggests that the complex represents a relatively independent folded subdomain.

Original languageEnglish (US)
Pages (from-to)463-468
Number of pages6
JournalJournal of Molecular Biology
Issue number2
StatePublished - Jan 15 1999

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Structural Biology


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