Determination of enthalpy and entropy changes for the binding to the Q(sub A) site in reverse micelles

Article Abstract:

The Q(sub A) binding sites of Rhodobacter sphaeroides reaction centers (RC) solubilized in phospholipid-based reverse micelles have been studied. The RC protein complex catalyzes the conversion of light into electrochemical energy through a series of electron-transfer reactions starting from a bacteriochlorophyll dimer down to several redox cofactors. Time-resolved absorbance measurements was used in measuring the binding of ubiquinone-10 to the Q(sub A) site. Results indicate that quinone binding to the primary site is stronger than in the Q(sub B) site based on the enthalpy and entropy changes.

Genetic aspects, Binding sites (Biochemistry), Active sites (Biochemistry), Ubiquinones, Bacteria, Photosynthetic, Photosynthetic bacteria

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Functionality of photosynthetic reaction centers in polyelectrolyte multilayers: Toward an herbicide biosensor

Article Abstract:

A membrane photosynthetic protein, the bacterial reaction center (RC), is adsorbed onto a glass surface by alternating deposition with the cationic polymer poly (dimethyldiallylammonium chloride) (PDDA) giving an ordinate polyelectrolyte multilayer (PEM) as the final outcome where the protein maintains its integrity and photoactivity over a period of many months. A framework has been suggested to demonstrate the interplay between forward and back electron-transfer processes upon continuous illumination, and the application of the PDDA-RC multilayers in herbicide bioassays is tested successfully.

Science & research, All Other Miscellaneous Chemical Product and Preparation Manufacturing, Chemical preparations, not elsewhere classified, Polyelectrolytes, Research, Membrane proteins, Adsorption, Properties, Structure, Chemical properties

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Influence of cardiolipin on the functionality of the Q(sub A) site of the photosynthetic bacterial reaction center

Article Abstract:

The effect of cardiolipin on the functionality if the Q(sub A) site of a photosynthetic reaction center (RC) is studied in RCs from the purple non-sulfur bacterium Rhodobacter sphaeroides using time-resolved absorbance measurements. The results reveal that there are two class of binding sites for cardiolipin, the high-affinity site is compatible with the binding site and the main affect of cardiolipin on the electron transfer is attributed to a destabilization of the charge-separated state.

Italy, Protein research, Photosynthesis

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