Ultrafast time-resolved carotenoid to-bacteriochlorophyll energy transfer in LH2 complexes from photosynthetic bacteria.
Ultrafast time-resolved carotenoid to-bacteriochlorophyll energy transfer in LH2 complexes from photosynthetic bacteria.
复制标题
DOI：
10.1021/jp711946w
复制
发表时间：
2008-08-28
期刊：
影响因子：
--
通讯作者：
Frank HA
中科院分区：
文献类型：
--
作者：
Cong H;Niedzwiedzki DM;Gibson GN;LaFountain AM;Kelsh RM;Gardiner AT;Cogdell RJ;Frank HA
在 293 和 10 K 下对从三种不同光合细菌菌株（Rhodobacter (Rb.) sphaeroides G1C、Rb.）分离的 LH2 色素-蛋白质复合物进行了稳态和超快时间分辨光学光谱研究。 sphaeroides 2.4.1（厌氧和需氧生长）和Rps。 Acidophila 10050。从这些菌株获得的 LH2 复合物分别含有类胡萝卜素、神经孢子烯、球状蛋白、球状蛋白酮和视紫红质葡糖苷。这些分子具有系统增加数量的π电子共轭碳碳双键。稳态吸收和荧光激发实验表明，从类胡萝卜素到细菌叶绿素的能量转移总效率与温度无关，并且对于含有神经孢子烯、球状蛋白、球状蛋白酮的LH2复合物几乎恒定在~90%，但对于含有视紫红质葡萄糖苷的复合物则下降至~53%。溶液中纯化类胡萝卜素的近红外 (NIR) 区域的超快瞬态吸收光谱揭示了 S1 (21Ag−) → S2 (11Bu+) 激发态跃迁的能量，当从稳态吸收测量确定的 S0 (11Ag−) → S2 (11Bu+) 跃迁的能量中减去该能量时，可以给出 类胡萝卜素的 S1 (21Ag−) 状态。超快光谱和时间数据集的全局拟合揭示了类胡萝卜素激发态去激发途径的动力学。这些途径包括能量转移至细菌叶绿素、类胡萝卜素的所谓S*状态的群体以及类胡萝卜素自由基阳离子(Car•+)的形成。研究发现，向细菌叶绿素的激发能量转移不同程度地通过不同类胡萝卜素的 S1 (11Ag−)、S2 (11Bu+) 和 S* 态进行分配。这是通过考虑分子的状态能量和光谱分布来理解的。一个重要的发现是，由于视紫红质葡萄糖苷的 S1 (21Ag−) 能量较低，与其他复合物相比，从这种状态到细菌叶绿素的能量转移的可能性明显较小。这项工作解决了一个长期存在的问题，即当紫色光合细菌的 LH2 复合物中类胡萝卜素的 π 电子共轭程度从 10 个扩展至 11 个共轭碳碳双键时，能量转移效率急剧下降的原因。
Steady-state and ultrafast time-resolved optical spectroscopic investigations have been carried out at 293 and 10 K on LH2 pigment-protein complexes isolated from three different strains of photosynthetic bacteria: Rhodobacter (Rb.) sphaeroides G1C, Rb. sphaeroides 2.4.1 (anaerobically and aerobically grown), and Rps. acidophila 10050. The LH2 complexes obtained from these strains contain the carotenoids, neurosporene, spheroidene, spheroidenone, and rhodopin glucoside, respectively. These molecules have a systematically increasing number of π-electron conjugated carbon-carbon double bonds. Steady-state absorption and fluorescence excitation experiments have revealed that the total efficiency of energy transfer from the carotenoids to bacteriochlorophyll is independent of temperature and nearly constant at ~90% for the LH2 complexes containing neurosporene, spheroidene, spheroidenone, but drops to ~53% for the complex containing rhodopin glucoside. Ultrafast transient absorption spectra in the near-infrared (NIR) region of the purified carotenoids in solution have revealed the energies of the S1 (21Ag−) → S2 (11Bu+) excited-state transitions which, when subtracted from the energies of the S0 (11Ag−) → S2 (11Bu+) transitions determined by steady-state absorption measurements, give precise values for the positions of the S1 (21Ag−) states of the carotenoids. Global fitting of the ultrafast spectral and temporal data sets have revealed the dynamics of the pathways of de-excitation of the carotenoid excited states. The pathways include energy transfer to bacteriochlorophyll, population of the so-called S* state of the carotenoids, and formation of carotenoid radical cations (Car•+). The investigation has found that excitation energy transfer to bacteriochlorophyll is partitioned through the S1 (11Ag−), S2 (11Bu+), and S* states of the different carotenoids to varying degrees. This is understood through a consideration of the energies of the states and the spectral profiles of the molecules. A significant finding is that, due to the low S1 (21Ag−) energy of rhodopin glucoside, energy transfer from this state to the bacteriochlorophylls is significantly less probable compared to the other complexes. This work resolves a long-standing question regarding the cause of the precipitous drop in energy transfer efficiency when the extent of π-electron conjugation of the carotenoid is extended from ten to eleven conjugated carbon–carbon double bonds in LH2 complexes from purple photosynthetic bacteria.
登录
查看更多内容
影响因子：
--
作者：
COSGROVE, SA;GUITE, MA;CHRISTENSEN, RL
通讯作者：
CHRISTENSEN, RL
影响因子：
2.8
作者：
Akahane, J;Rondonuwu, FS;Koyama, Y
通讯作者：
Koyama, Y
影响因子：
3.3
作者：
Desamero, RZB;Chynwat, V;Frank, HA
通讯作者：
Frank, HA
DOI：
10.1016/0005-2728(86)90208-2
发表时间：
1986-03-12
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
ANGERHOFER, A;COGDELL, RJ;HIPKINS, MF
通讯作者：
HIPKINS, MF
影响因子：
15
作者：
COTTON, TM;VANDUYNE, RP
通讯作者：
VANDUYNE, RP