Reassociation of All-<i>trans</i>-3,4-Dihydroanhydrorhodovibrin with LH1 Subunits Isolated from<i>Rhodospirillum rubrum</i>: Selective Binding of All-<i>trans</i>Isomer from Mixture of<i>cis</i>- and<i>trans</i>-Isomers
作者:Mai Yamamoto、Tomoko Horibe、Yoshiaki Nishisaka、Shuichi Suzuki、Masatoshi Kozaki、Ritsuko Fujii、Matsumi Doe、Mamoru Nango、Keiji Okada、Hideki Hashimoto
DOI:10.1246/bcsj.20120230
日期:2013.1.15
The reassociation of carotenoids with the photosynthetic light-harvesting 1 (LH1) pigment–protein complex has proven to be a powerful technique to investigate the function of carotenoids. We have recently investigated the reassociation of the carotenoids, spirilloxanthin (number of conjugated C=C bonds (n) = 13), anhydrorhodovibrin (n = 12), rhodopin (n = 11), and spheroidene (n = 10)) with carotenoid-depleted LH1 subunits isolated from Rhodospirillum rubrum. In the case of the rhodopin complex, small anomalies were observed in the absorption maximum of the Qy band of bacteriochlorophyll a (BChl a Qy) and the singlet–singlet energy-transter efficiency of 1carotenoid* → 1BChl a* within the LH1–carotenoid complex. The reason for these anomalies could probably be ascribed to the rhodopin hydroxy group. To investigate this further, reassociation experiments of the LH1 complex with hydroxy-protected rhodopin, all-trans-3,4-dihydroanhydrorhodovibrin (1), were conducted. We observed a normal absorption maximum (883 nm) of the BChl a Qy band in the LH1–1 complex. The energy-transter efficiency of 1carotenoid* (11*) → 1BChl a* was found to be 53%, giving a good correlation with the other carotenoids. Furthermore, we found a preferential complexation of all-trans-1 to carotenoid-depleted LH1 from a 1:1 mixture of all-trans-1 and cis-1 (cis-1 consists of a 1:1 mixture of 5-cis-5′-trans-1 and 5-trans-5′-cis-1).
类胡萝卜素与光合光捕获1(LH1)色素-蛋白复合物的重新结合被证明是一种强有力的技术,用于研究类胡萝卜素的功能。我们最近研究了从红色螺旋菌中分离出的缺失类胡萝卜素的LH1亚基与类胡萝卜素的重新结合,包括螺旋胡萝卜素(共轭C=C键数(n) = 13)、无水红藻素(n = 12)、红苯(n = 11)和球藻烯(n = 10)。在红苯复合物的情况下,观察到细菌叶绿素a(BChl a) Qy带的吸收峰值存在小的异常现象,以及LH1-类胡萝卜素复合物中1类胡萝卜素* → 1 BChl a*的单重态-单重态能量转移效率。造成这些异常的原因可能归因于红苯的羟基。为了进一步研究这一点,进行了LH1复合物与羟基保护红苯的重新结合实验,氢化无水红藻素(1)的实验。我们观察到LH1-1复合物中BChl a Qy带的吸收峰值正常(883纳米)。发现1类胡萝卜素*(11*)→ 1 BChl a*的能量转移效率为53%,与其他类胡萝卜素有良好的相关性。此外,我们发现全反式-1与缺失类胡萝卜素的LH1之间存在优先配合,从全反式-1和顺式-1(顺式-1是5-顺式-5′-反式-1与5-反式-5′-顺式-1的1:1混合物)1:1混合物中得到了这一结果。