Andreas Labahn

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Flash-induced redox changes of b-type and c-type cytochromes have been studied in chromatophores from the aerobic photosynthetic bacterium Roseobacter denitrificans under redox-controlled conditions. The flash-oxidized primary donor P+ of the reaction center (RC) is rapidly re-reduced by heme H1 (Em,7 = 290 mV), heme H2 (Em,7 = 240 mV) or low-potential(More)
The primary electron donor P700 of photosystem I is a dimer comprised of chlorophyll a (P(B)) and chlorophyll a' (P(A)). P(A) is involved in a hydrogen bond network with several surrounding amino acid residues and a nearby water molecule. To investigate the influence of hydrogen bond interactions on the properties of P700, the threonine at position A739,(More)
The direct charge recombination rates from the primary quinone, k AD (D+Q A − → DQA) and the secondary quinone, k BD (D+Q B − → DQB), in reaction centers from Rhodobacter sphaeroides were measured as a function of the free energy differences for the processes, ΔG AD 0 and ΔG BD 0 , respectively. Measurements were performed at 21 °C on a series of mutant(More)
Roseobacter denitrificans (Erythrobacter species strain OCh114) synthesizes bacteriochlorophyll a (BChl) and the photosynthetic apparatus only in the presence of oxygen and is unable to carry out primary photosynthetic reactions and to grow photosynthetically under anoxic conditions. The puf operon of R. denitrificans has the same five genes in the same(More)
Cells contain a multitude of different chemical reaction paths running simultaneously and quite independently next to each other. This amazing feat is enabled by molecular recognition, the ability of biomolecules to form stable and specific complexes with each other and with their substrates. A better understanding of this process, i.e. of the kinetics,(More)
Using a confocal fluorescence microscope with an avalanche photodiode as detector, we studied the fluorescence of the tetramethylrhodamine labeled F1 part of the H+-ATPase from Escherichia coli, EF1, carrying the gammaT106-C mutation [Aggeler, J.A. and Capaldi, R.A. (1992) J. Biol. Chem. 267, 21355-21359] in aqueous solution upon excitation with a(More)
The membrane-bound H(+)-ATPase from chloroplasts, CF0F1, was brought into the active, reduced state by illumination in the presence of thioredoxin and dithiothreitol. The endogenous nucleotides were removed by a washing procedure so that the active, reduced enzyme contained one tightly bound ATP per CF0F1. When [14C]ADP was added in substoichiometric(More)
Human neutrophil elastase (HNE), a serine protease, is involved in the regulation of inflammatory processes and controlled by endogenous proteinase inhibitors. Abnormally high levels of HNE can cause degradation of healthy tissues contributing to inflammatory diseases such as rheumatoid arthritis, and also psoriasis and delayed wound healing. In(More)
Contradictory results on the effectiveness of energy transfer from the light harvesting complex 2 (LH2) directly to the reaction center (RC) in mutant strains lacking the core light-harvesting complex 1 (LH1) have been obtained with cells of Rhodobacter capsulatus and Rhodobacter sphaeroides. A LH1− mutant of Rhodovulum sulfidophilum, named rsLRI, was(More)
Human neutrophil elastase (HNE) is a serine protease, which is present in its active form in inflamed tissue as well as in psoriatic lesions. In extension of our research on natural compounds as inhibitors of HNE or of its release, several phenolics of different size were tested. The ellagitannins agrimoniin and pedunculagin were the most potent direct HNE(More)