Excitation wavelength dependent spectral evolution in Rhodobacter sphaeroides R-26 reaction centers at low temperatures: the Qy transition region

Article Abstract:

The femtosecond (fs) transient absorbance spectroscopy was used as a function of excitation length to study the spectral evolution associated with energy and electron transfer in quinone-depleted reaction centers from Rhodobacter sphaeroides strain R-26 at low temperatures. Results indicated that the energy transfer from bacteriopheophytins (H) to bacteriochlorophyll monomer (B) takes place on the 100 fs or less time scale, while that from B to bacteriochlorophyll dimer (P) occurs in about 100-150 fs. Moreover, the temperature dependence of the energy transfer rate was found to be weak.

Electron transport, Energy transfer

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B-side electron transfer promoted by absorbance of multiple photons in Rhodobacter sphaeroides R-26 reaction centers

Article Abstract:

A study was conducted to analyze the excitation wavelength dependence and the excitation intensity dependence of the formation of charge-separated states on the A- and B-side of the reaction center of Rhodobacter sphaeroides. Results indicated that high-intensity 595 nm excitation led to a long-lived bleaching of the B-side bacteriopheophytin. Findings also showed the possibility of inducing about 40% of electron transfer along the B-branch of the bacterial reaction using high-intensity excitation.

Photons, Oxidation-reduction reaction, Oxidation-reduction reactions

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Fluorescence intensity fluctuations of individual labeled DNA fragments and a DNA binding protein in solution at the single molecule level: a comparison of photobleaching, diffusion, and binding dynamics

Article Abstract:

A new study investigates the fluorescence intensity fluctuations of individual DNA fragments and a DNA binding protein in solution. Photobleaching, diffusion and binding dynamics are compared.

Biochemistry, Protein binding, DNA-ligand interactions, Molecular microbiology, DNA binding

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