tailieunhanh - Báo cáo Y học: Caged O2 Reaction of cytochrome bo3 oxidase with photochemically released dioxygen from a cobalt peroxo complex

We developed the synthesis of the caged oxygen donor (l-peroxo)(l-hydroxo)bis[bis(bipyridyl)cobalt(III)] complex (HPBC) as nitrate salt,which has,compared with the perchlorate-form described previously [MacArthur,R., Sucheta,A.,Chong,. & Einarsdottir,O¨ . (1995) Proc. Natl Acad. Sci. USA, 92,8105–8109],greatly enhanced solubility. Now,the quantum efficiency of the photolytical release of dioxygenwas determined tobe per photon at a laser wavelength of 308 nm,which was used to observe biological reactions | Eur. J. Biochem. 269 30 2to 22002 FEBS 2002 doi Caged O2 Reaction of cytochrome bo3 oxidase with photochemically released dioxygen from a cobalt peroxo complex Claudia Ludovici Roland Frohlich Karsten Vogtt Bjorn Mamatt and Mathias Liibben Lehrstuhl fur Biophysik Ruhr-Universităt Bochum Germany We developed the synthesis of the caged oxygen donor p-peroxo p-hydroxo bis bis bipyridyl cobalt III complex HPBC as nitrate salt whihh hits compared with the perchlorate-form described previously MacArthur R. Sucheta A. Chong. . Ô. 1995 Proc. Natl Acad. Sci. USA 92 8155-8199g e i y ly enncnced solubility. Now the quantum efficiency of the photolyiiarl release of dioxygen was determined to be per photon at a laser wavelength of 308 nm wlchlt was usdd to observe biological reactions. The X-ray structure of HPBC has been solved and the molecular interactions of photochemically generated oxygen with cytochrome oxidase were investigated with optical and FT-IR spectroscopy it acts as acceptor of electrons transferred from prereduced cytochrome bo3 the heme-copper oxidase Com Escherichia coli. FT-IR spectra revealed typical absorbance difference changes in the carbonyl region of cytochrome bo3 u uppotted by bandshifts due to solvent isotope exchange and by assignment using site-directed mutants. IR difference spectra of the photooxidation reaction using the caged oxygen compound and of the photoreduction reaction using the caged electron donor FMN have inverted shapes. The spectroscopic signals of carboxyl groups are thus equivalent in both reactions the use of chemically produced oxygen allows the observation of the ongoing molecular changes of cytochrome bo3 oxidase under quasi-physiological conditions. Keywords cytochrome oxidase caged compound FT-IR spectroscopy oxygen p-peroxo cobalt complex. Cytochrome oxidases are hetero-oligomeric integral membrane proteins that belong to the superfamily of heme-copper oxidases 1 2 . .