A protein conformational change associated with the photoreduction of the primary and secondary quinones in the bacterial reaction center

AbstractA comparison is made between the PQA → P+Q−A and PQAQB → P+QAQ−B transitions in Rps. viridis and Rb. sphaeroides reaction centers (RCs) by the use of light-induced Fourier transform infrared (FTIR) difference spectroscopy. In Rb. sphaeroides RCs, we identify a signal at 1650 cm−1 which is present in the P+QA-minus-PQA spectrum and not in the P+QAQ−B-minus-PQAQB spectrum. In contrast, this signal is present in both P+Q−A-minus-PQ−A and P+QAQ−B-minus-PQAQB spectra of Rps. viridis RCs. These data are interpreted in terms of a conformational change of the protein backbone near QA (possible at the peptide CO of a conserved alanine residue in the QA pocket) and of the different bonding interactions of QB with the protein in the RC of the two species

Vorrichtung und Verfahren zur Darstellung eines Objektes mittels Durchstrahlung

The invention relates to a device comprising a radiation source (18) and a radiation receiver (20), two robot arms (10, 14) for positioning the radiation source and the radiation receiver, a control device (22) for controlling the robot arms, and a processing device (24) for reconstructing a data set for imaging the object (26), in order to display the object by means of x-ray examination