ENDOR spectroscopy reveals light induced movement of the H-bond from Ser-L223 upon forming the semiquinone (Q(B)(-)(*)) in reaction centers from Rhodobacter sphaeroides.

ABSTRACT: Proton ENDOR spectroscopy was used to monitor local conformational changes in bacterial reaction centers (RC) associated with the electron-transfer reaction DQB --> D+*QB-* using mutant RCs capable of photoreducing QB at cryogenic temperatures. The charge separated state D+*QB-* was studied in mutant RCs formed by either (i) illuminating at low temperature (77 K) a sample frozen in the dark (ground state protein conformation) or (ii) illuminating at room temperature prior to and during freezing (charge separated state protein conformation). The charge recombination rates from the two states differed greatly (>10(6) fold) as shown previously, indicating a structural change (Paddock et al. (2006) Biochemistry 45, 14032-14042). ENDOR spectra of QB-* from both samples (35 GHz, 77 K) showed sev

SUBMITTER: Paddock ML 

PROVIDER: S-EPMC2597558 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature