中文摘要：

采用动态光散射、透射电子显微镜、紫外-可见吸收光谱和拉曼光谱对比研究了处于表面活性剂胶束和脂质体磷脂双分子层中的Thermochromatium（Tch.）tepidum LH2的光谱响应.结果表明,与在表面活性剂胶束中相比,双分子层脂膜中LH2的Spirilloxanthin（一种含有13个共轭双键的类胡萝卜素）构象有明显差异;表面活性剂及磷脂分子端基的荷电状态对B850-Qy吸收谱有显著影响;Ca2＋结合导致B850 Qy吸收谱带红移和增色,而H＋结合则使该吸收谱带蓝移和减色.对LH2脱辅基蛋白氨基酸序列的分析结果表明,Ca2＋和H＋的结合位点可能位于α脱辅基蛋白的C-端一侧.B850 Qy吸收谱带对Ca2＋和H＋的响应特性可能与Tch.tepidum适应其生存环境的能力有关.

英文摘要：

By the use of dynamic light scattering （ DLS）, transmission electron microscopy （ TEM）, UV-Vis and resonance Raman spectroscopy, the properties of LH2 from Thermochromatium （ Tch. ） tepidum in two detergent micelles and in liposome were studied, respectively. The results show that in LH2-liposome the conformation of spirilloxanthin, an incorporated longer chain carotenoid, is obviously different from that in detergent micelles. The charge state of the terminal groups of detergents or lipids is the key factor affecting the B850 absorption. Generally, the calcium ions cause red-shift of the B850 absorption and hyperehromieity, while the proton has the opposite effect. Based on the amino acid sequence analysis, several amino acid residues on the C-terminus of a apo-protein were proposed to constitute the potential binding site for the calcium ion and proton. Such Ca2＋- and H＋-regulated changes of B850 absorption might be an adaptive mechanism to the living environment for this species.