Probing the effect of the binding site on the electrostatic behavior of a series of carotenoids reconstituted into the light-harvesting 1 complex from purple photosynthetic bacterium Rhodospirillum rubrum detected by stark spectroscopy.
Probing the effect of the binding site on the electrostatic behavior of a series of carotenoids reconstituted into the light-harvesting 1 complex from purple photosynthetic bacterium Rhodospirillum rubrum detected by stark spectroscopy.
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DOI：
10.1021/jp801773j
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发表时间：
2008-07
期刊：
影响因子：
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通讯作者：
K. Nakagawa;Satoru Suzuki;R. Fujii;A. Gardiner;R. Cogdell;M. Nango;H. Hashimoto
中科院分区：
文献类型：
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作者：
K. Nakagawa;Satoru Suzuki;R. Fujii;A. Gardiner;R. Cogdell;M. Nango;H. Hashimoto
用具有不同数目的C=C共轭双键的一系列类胡萝卜素分子进行来自紫色光合细菌Rhodocellum rubrum S1的LH 1复合物的重构。因为，正如我们之前所表明的，一些添加的类胡萝卜素倾向于聚集，然后保留在重构的LH 1复合物中（Nakagawa，K.; Suzuki，S.; Fujii，R.;加德纳，A.T.; Cogdell，R.J.; Nango，M.; Hashimoto，H.光合作用。Res. 2008，95，339-344），引入使用蔗糖密度梯度离心的进一步纯化步骤以提高最终重构样品的纯度。测得的吸收，荧光激发，和斯塔克光谱的LH 1复合物重建与natural，naturalloxanthin-containing，LH 1复合物的RS是相同的。红花S1。这表明，在这两个LH 1复合物中的类胡萝卜素和细菌叶绿素a（BChl a）分子周围的静电环境基本上是相同的。然而，在与视紫红质或spheroidene重构的LH 1复合物中，在BChl a Qy吸收带处的波长最大值与天然LH 1复合物的波长最大值略有不同。BChl a Qy吸收带的跃迁能量的这些差异可以使用该吸收带的非线性光学参数的值来解释，即，极化率变化Tr（Δ α）和静态偶极距变化|德尔塔穆|在光激发时，如使用斯塔克光谱法测定的。天然LH 1复合物（ES）中BChl a周围的局部电场被确定为约3.0 × 10（6）V/cm。此外，在重建的LH 1复合物中的类胡萝卜素的非线性光学参数的值的基础上，它是可能的建议，类胡萝卜素，脱水血红蛋白和spheroidene，在LH 1复合物的构象类似的晶体结构中的Rhodopin葡萄糖苷的LH 2复合物从嗜酸红球藻10050。
Reconstitutions of the LH1 complexes from the purple photosynthetic bacterium Rhodospirillum rubrum S1 were performed with a range of carotenoid molecules having different numbers of C=C conjugated double bonds. Since, as we showed previously, some of the added carotenoids tended to aggregate and then to remain with the reconstituted LH1 complexes (Nakagawa, K.; Suzuki, S.; Fujii, R.; Gardiner, A.T.; Cogdell, R.J.; Nango, M.; Hashimoto, H. Photosynth. Res. 2008, 95, 339-344), a further purification step using a sucrose density gradient centrifugation was introduced to improve purity of the final reconstituted sample. The measured absorption, fluorescence-excitation, and Stark spectra of the LH1 complex reconstituted with spirilloxanthin were identical with those obtained with the native, spirilloxanthin-containing, LH1 complex of Rs. rubrum S1. This shows that the electrostatic environments surrounding the carotenoid and bacteriochlorophyll a (BChl a) molecules in both of these LH1 complexes were essentially the same. In the LH1 complexes reconstituted with either rhodopin or spheroidene, however, the wavelength maximum at the BChl a Qy absorption band was slightly different to that of the native LH1 complexes. These differences in the transition energy of the BChl a Qy absorption band can be explained using the values of the nonlinear optical parameters of this absorption band, i.e., the polarizability change Tr(Deltaalpha) and the static dipole-moment change |Deltamu| upon photoexcitation, as determined using Stark spectroscopy. The local electric field around the BChl a in the native LH1 complex (ES) was determined to be approximately 3.0x10(6) V/cm. Furthermore, on the basis of the values of the nonlinear optical parameters of the carotenoids in the reconstituted LH1 complexes, it is possible to suggest that the conformations of carotenoids, anhydrorhodovibrin and spheroidene, in the LH1 complex were similar to that of rhodopin glucoside in crystal structure of the LH2 complex from Rhodopseudomonas acidophila 10050.