Redox-controlled backbone dynamics of human cytochrome c revealed by {sup 15}N NMR relaxation measurements

Journal Article · Fri Jul 23 04:00:00 EDT 2010 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2010.06.065· OSTI ID:22202701

Sakamoto, Koichi ^[1]; Kamiya, Masakatsu ^[2]; Uchida, Takeshi ^[1]; Kawano, Keiichi ^[2]; Ishimori, Koichiro ^[1]

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1. Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)
2. Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan)

Research highlights: {yields} The dynamic parameters for the backbone dynamics in Cyt c were determined. {yields} The backbone mobility of Cyt c is highly restricted due to the covalently bound heme. {yields} The backbone mobility of Cyt c is more restricted upon the oxidation of the heme. {yields} The redox-dependent dynamics are shown in the backbone of Cyt c. {yields} The backbone dynamics of Cyt c would regulate the electron transfer from Cyt c. -- Abstract: Redox-controlled backbone dynamics in cytochrome c (Cyt c) were revealed by 2D {sup 15}N NMR relaxation experiments. {sup 15}N T{sub 1} and T{sub 2} values and {sup 1}H-{sup 15}N NOEs of uniformly {sup 15}N-labeled reduced and oxidized Cyt c were measured, and the generalized order parameters (S{sup 2}), the effective correlation time for internal motion ({tau}{sub e}), the {sup 15}N exchange broadening contributions (R{sub ex}) for each residue, and the overall correlation time ({tau}{sub m}) were estimated by model-free dynamics formalism. These dynamic parameters clearly showed that the backbone dynamics of Cyt c are highly restricted due to the covalently bound heme that functions as the stable hydrophobic core. Upon oxidation of the heme iron in Cyt c, the average S{sup 2} value was increased from 0.88 {+-} 0.01 to 0.92 {+-} 0.01, demonstrating that the mobility of the backbone is further restricted in the oxidized form. Such increases in the S{sup 2} values were more prominent in the loop regions, including amino acid residues near the thioether bonds to the heme moiety and positively charged region around Lys87. Both of the regions are supposed to form the interaction site for cytochrome c oxidase (CcO) and the electron pathway from Cyt c to CcO. The redox-dependent mobility of the backbone in the interaction site for the electron transfer to CcO suggests an electron transfer mechanism regulated by the backbone dynamics in the Cyt c-CcO system.

• OSTI ID: 22202701
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 2 Vol. 398; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
AMINO ACIDS
ELECTRON TRANSFER
HEME
NITROGEN 15
NUCLEAR MAGNETIC RESONANCE
ORDER PARAMETERS
OXIDASES