Cytochrome c electronic structure characterization toward the analysis of electron transfer mechanism.
Seventy-four kinds of cytochrome c sequences have been compared in order to determine the conserved residues and residues of which the characters are conserved. Twenty-three residues are invariant throughout all the aligned sequences, while the residues at 17 other positions share common characters. The prosthetic group as well as these conserved and character-conserved residues are considered to constitute a model molecule to elucidate the electron transfer process in cytochrome c. Their coordinates in the structure of tuna cytochrome c are extracted, and an extended Hückel molecular orbital calculation has been executed on this molecule. The examination of the shapes and the energy levels of the resulting MOs has suggested that three nearly degenerate HOMOs might play an important role in the electron transfer. These HOMOs are exposed to the protein surface around the heme, Cys-17, and Phe-82. A delocalized electron system developing in these regions is proposed to be the electron transfer pathway of cytochrome c.
Faculty of Science, Kwansei Gakuin University, Hyogo.
H
H
Nakagawa
Y
Y
Koyama
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T
Okada
D000595:Amino Acid Sequence; D016384:Consensus Sequence; D003574:Cytochrome c Group / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D003574:Cytochrome c Group