Excited States, Electron-Transfer Reactions, and Intermediates in Bacterial Photosynthetic Reaction Centers
نویسنده
چکیده
ragonal transition at the equilibrium state occurs at about 550 OC. Here we have shown that under CH, atmosphere the onset temperature is lowered by at least 150 "C. This result is consistent with the assumption that the out-diffusion rate of oxygen in the YBaCuO compound is limited by a surface barrier of 1.7 eV, which is involved in the surface diffusion of 0species and the further formation and desorption of 02.13 In the presence of methane this surface barrier is lowered as a result of the strong J . Phys. Chem. 1989, 93, 8280-8294
منابع مشابه
Distance Dependence of Electron-Transfer Reactions in Organized Systems: The Role of Superexchange and Non-Condon Effects in Photosynthetic Reaction Centers
Extremely long distance electron transfer is observed in some photosynthetic reaction centers. For several charge recombination reactions, the rate appears to fall off much more slowly with distance than expected from simple models. A general model is proposed for sequential electron-transfer reactions, which often occur in biological systems, in which each ion pair in the forward direction act...
متن کاملMechanism of the initial charge separation in bacterial photosynthetic reaction centers.
The initial electron transfer in reaction centers from Rhodobacter sphaeroides R26 was studied by a subpicosecond transient pump-probe technique. The measured kinetics at various wavelengths were analyzed and compared with several mechanisms for electron transfer. An unambiguous determination of the initial electron transfer mechanism in reaction centers cannot be made by studying the anion abs...
متن کاملOscillations in the Spontaneous Fluorescence from Photosynthetic Reaction Centers
The spontaneous fluorescence from the special pair primary electron donor in bacterial photosynthetic reaction centers has been measured at low temperature using fluorescence up-conversion following excitation of the special pair with 80 fs pulses from a mode-locked Ti:sapphire laser. Oscillations are observed during the first few picoseconds of the decay. The frequency of the oscillations and ...
متن کاملLong-time quantum simulation of the primary charge separation in bacterial photosynthesis.
Accurate quantum mechanical simulations of the primary charge transfer in photosynthetic reaction centers are reported. The process is modeled by three coupled electronic states corresponding to the photoexcited chlorophyll special pair (donor), the reduced bacteriopheophytin (acceptor), and the reduced accessory chlorophyll (bridge) that interact with a dissipative medium of protein and solven...
متن کاملInitial electron-transfer in the reaction center from Rhodobacter sphaeroides.
The initial electron transfer steps in the photosynthetic reaction center of the purple bacterium Rhodobacter sphaeroides have been investigated by femtosecond time-resolved spectroscopy. The experimental data taken at various wavelengths demonstrate the existence of at least four intermediate states within the first nanosecond. The difference spectra of the intermediates and transient photodic...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2001