title: Investigation of the redox-dependent modulation of structure and dynamics in human cytochrome c.
abstract: Redox-dependent changes in the structure and dynamics of human cytochrome c (Cyt c) were investigated by solution NMR. We found significant structural changes in several regions, including residues 23-28 (loop 3), which were further corroborated by chemical shift differences between the reduced and oxidized states of Cyt c. These differences are essential for discriminating redox states in Cyt c by cytochrome c oxidase (CcO) during electron transfer reactions. Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion experiments identified that the region around His33 undergoes conformational exchanges on the μs-ms timescale, indicating significant redox-dependent structural changes. Because His33 is not part of the interaction site for CcO, our data suggest that the dynamic properties of the region, which is far from the interaction site for CcO, contribute to conformational changes during electron transfer to CcO.
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Mizue
authors.initials: M
authors.lastname: Imai
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Tomohide
authors.initials: T
authors.lastname: Saio
authors.affiliation: Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kumeta
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uchida
authors.affiliation: Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan.
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Inagaki
authors.affiliation: Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan. Electronic address: koichiro@sci.hokudai.ac.jp.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ishimori
mesh_terms: D001665:Binding Sites; D045304:Cytochromes c / Q000737:chemistry* / Q000648:ultrastructure*; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: D045304:Cytochromes c; D010100:Oxygen
keywords: Cytochrome c; Dynamics; Electron transfer; Solution structure