Characterization of the pH-dependent resonance Raman transitions of archaeal and bacterial Rieske [2Fe-2S] proteins.
The pH-dependent resonance Raman (RR) spectral changes of the cytochrome bc1-associated, high-potential Rieske proteins have frequently been invoked to explain the redox-linked ionization behavior. We report herein RR spectral data of archaeal and bacterial Rieske proteins that directly demonstrate the pH-dependent changes near and above pKa,ox2, but not around pKa,ox1, of the visible circular dichroism (CD) transitions. The RR spectral changes are attributed to modification of the immediate [2Fe-2S] cluster environment due to deprotonation of some exchangeable amide groups in the polypeptide backbone, rather than previously assumed simple changes of the Fe-Nimid stretching vibrations.
Iwasaki
Toshio
T
Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. tiwasaki@nms.ac.jp
Kounosu
Asako
A
Kolling
Derrick R J
DR
Crofts
Antony R
AR
Dikanov
Sergei A
SA
Jin
Akihisa
A
Imai
Takeo
T
Urushiyama
Akio
A
D019843:Archaeal Proteins / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D014450:Electron Transport Complex III / Q000737:chemistry*; D005288:Ferredoxins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D016944:Sulfolobus / Q000737:chemistry
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; C037989:Rieske iron-sulfur protein; D014450:Electron Transport Complex III