Characterization of the pH-Dependent Resonance Raman Transitions of Archaeal and Bacterial Rieske [2Fe−2S] Proteins
2004; American Chemical Society; Volume: 126; Issue: 15 Linguagem: Inglês
10.1021/ja031976p
ISSN1943-2984
AutoresToshio Iwasaki, Asako Kounosu, Derrick R.J. Kolling, Antony R. Crofts, Sergei A. Dikanov, Akihisa Jin, Takeo Imai, Akio Urushiyama,
Tópico(s)Enzyme Structure and Function
ResumoThe 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.
Referência(s)