Biomaterial Database

The orientations of transition moments in reaction centers of Rhodopseudomonas sphaeroides, computed from data of linear dichroism and photoselection measurements. 1979

R K Clayton, and C N Rafferty, and A Vermeglio

Linear dichroism measurements of reaction centers of Rhodopseudomonas sphaeroides in stretched gelatin films have yielded angles that various optical transition moments make with an axis of symmetry in the reaction center. Photoselection experiments have yielded angles that certain transition moments make with each other. We have combined these data so as to compute the orientations of the Qx and Qy transition moments of the two molecules of bacteriopheophytin and of the bacteriochlorophyll special pair (photochemical electron donor) in the reaction center. Orientations are expressed in spherical polar coordinates with the symmetry axis as the pole. We have also computed additional angles between pairs of transition moments. In this treatment we have assumed that the bacteriopheophytins are independent monomers with little or no exciton coupling.

UI	MeSH Term	Description	Entries
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010674	Pheophytins	Chlorophylls from which the magnesium has been removed by treatment with weak acid.	Pheophytin
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002734	Chlorophyll	Porphyrin derivatives containing magnesium that act to convert light energy in photosynthetic organisms.	Phyllobilins,Chlorophyll 740
D001429	Bacteriochlorophylls	Pyrrole containing pigments found in photosynthetic bacteria.	Bacteriochlorophyll
D012242	Rhodobacter sphaeroides	Spherical phototrophic bacteria found in mud and stagnant water exposed to light.	Rhodopseudomonas sphaeroides,Rhodobacter spheroides,Rhodopseudomonas spheroides
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.