Song S-H, Dick B, Penzkofer A, Hegemann P
Institut für Physikalische und Theoretische Chemie, Universität Regensburg, D-93053 Regensburg, Germany.
J Photochem Photobiol B. 2007 Apr 2;87(1):37-48. doi: 10.1016/j.jphotobiol.2006.12.007. Epub 2007 Jan 10.
The photo-excitation dynamics of the mutants LOV1-C57S and LOV2-C250S of the LOV-domains of the phototropin photoreceptor phot from the green alga Chlamydomonas reinhardtii is investigated by absorption and fluorescence studies. The LOV domains fused to a maltose binding protein (MBP) are expressed in Escherichia coli. The mutants were studied under aerobic conditions in aqueous solution at pH 8. Blue-light exposure reduced the fully oxidized flavin mononucleotide, FMN(ox), to FMN semiquinone, FMNH*, (quantum efficiency around 1%) which further reduced to FMN hydroquinone, FMN(red)H(2) or FMN(red)H(-) (quantum efficiency ca. 3 x 10(-5)). In the dark both reduced forms recovered back to the oxidized form on a minute timescale. Besides photoreduction, blue-light photo-excitation of the mutants resulted in photoproduct formation (efficiency in the 2 x 10(-4) - 10(-3) range). Photo-reaction schemes for the mutants are discussed.
通过吸收和荧光研究，对莱茵衣藻光趋性光感受器phot的LOV结构域的突变体LOV1-C57S和LOV2-C250S的光激发动力学进行了研究。与麦芽糖结合蛋白（MBP）融合的LOV结构域在大肠杆菌中表达。在pH 8的水溶液中，在有氧条件下对突变体进行了研究。蓝光照射使完全氧化的黄素单核苷酸FMN(ox)还原为FMN半醌FMNH*（量子效率约为1%），后者进一步还原为FMN对苯二酚FMN(red)H(2)或FMN(red)H(-)（量子效率约为3×10⁻⁵）。在黑暗中，两种还原形式在分钟时间尺度上恢复为氧化形式。除了光还原外，突变体的蓝光光激发还导致光产物形成（效率在2×10⁻⁴ - 10⁻³范围内）。讨论了突变体的光反应方案。
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