Function of membrane protein in silica nanopores: Incorporation of photosynthetic light-harvesting protein LH2 into FSM
Function of membrane protein in silica nanopores: Incorporation of photosynthetic light-harvesting protein LH2 into FSM
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DOI：
10.1021/jp0540860
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发表时间：
2006-01-26
影响因子：
3.3
通讯作者：
Itoh, S
中科院分区：
文献类型：
--
作者：
Oda, I;Hirata, K;Itoh, S
将大量的功能性膜蛋白复合体引入到具有纳米级蜂窝状六方柱状结构的折叠片二氧化硅介孔材料中。光合作用捕光复合体LH2是一种典型的膜蛋白，具有直径7.3 nm的圆柱形结构，含有27个细菌叶绿素a和9个类胡萝卜素分子。该复合体能捕获厌氧紫色光合细菌Thennochromatum tepium.中的光能。用光学方法和N-2吸附等温线测定了LH2在FSM上的吸附量。内径为7.9 nm和2.7 nm的FSM化合物对LH2的吸附分别为1.11和0.24 mg/mg FSM，表明LH2对直径为7.9 nm的疏水纳米孔具有较高的比亲和力。吸附在FSM上的LH2表现出几乎完整的细菌-叶绿素吸收带，并且在激发能量的捕获和转移方面表现出充分的活性。FSM内部的LH2络合物表现出细菌-叶绿素(B850)激子型吸收带的热稳定性增加，表明具有较高的圆对称性。疏水二氧化硅纳米孔内部的环境可以为膜蛋白揭示其功能提供新的基质。硅膜蛋白加合物可用于构建新的探针和反应体系。
A high amount of functional membrane protein complex was introduced into a folded-sheet silica mesoporous material (FSM) that has nanometer-size pores of honeycomb-like hexagonal cylindrical structure inside. The photosynthetic light-harvesting complex LH2, which is a typical membrane protein, has a cylindrical structure of 7.3 nm diameter and contains 27 bacteriochlorophyll a and nine carotenoid molecules. The complex captures light energy in the anoxygenic thermophilic purple photosynthetic bacterium Thennochromatium tepidum. The amount of LH2 adsorbed to FSM was determined optically and by the adsorption isotherms of N-2. The FSM compounds with internal pore diameters of 7.9 and 2.7 nm adsorbed LH2 at 1.11 and 0.24 mg/mg FSM, respectively, suggesting the high specific affinity of LH2 to the interior of the hydrophobic nanopores with a diameter of 7.9 nm. The LH2 adsorbed to FSM showed almost intact absorption bands of bacteriochlorophylls, and was fully active in the capture and transfer of excitation energy. The LH2 complex inside the FSM showed increased heat stability of the exciton-type absorption band of bacteriochlorophylls (B850), suggesting higher circular symmetry. The environment inside the hydrophobic silica nanopores can be a new matrix for the membrane proteins to reveal their functions. The silica-membrane protein adduct will be useful for the construction of new probes and reaction systems.