Fyfe P K, Jones M R
Division of Biological Chemistry and Molecular Microbiology, Faculty of Life Sciences, University of Dundee, Nethergate, Dundee DD1 4HN, UK.
Biochem Soc Trans. 2005 Nov;33(Pt 5):924-30. doi: 10.1042/BST20050924.
Reaction centres are membrane-embedded pigment-protein complexes that transduce the energy of sunlight into a biologically useful form. The most heavily studied reaction centres are the PS-I (Photosystem I) and PS-II complexes from oxygenic phototrophs, and the reaction centre from purple photosynthetic bacteria. A great deal is known about the compositions and structures of these reaction centres, and the mechanism of light-activated transmembrane electron transfer, but less is known about how they interact with other components of the photosynthetic membrane, including the membrane lipids. X-ray crystallography has provided high-resolution structures for PS-I and the purple bacterial reaction centre, and revealed binding sites for a number of lipids, either embedded in the protein interior or attached to the protein surface. These lipids play a variety of roles, including the binding of cofactors and the provision of structural support. The challenges of modelling surface-associated electron density features such as lipids, detergents, small amphiphiles and ions are discussed.
反应中心是嵌入膜中的色素-蛋白质复合物，可将太阳光的能量转化为生物可用的形式。研究最为深入的反应中心是来自产氧光合生物的光系统I（PS-I）和光系统II复合物，以及来自紫色光合细菌的反应中心。关于这些反应中心的组成、结构以及光激活跨膜电子转移的机制，我们已经了解很多，但对于它们如何与光合膜的其他成分（包括膜脂）相互作用，我们所知甚少。X射线晶体学已经为PS-I和紫色细菌反应中心提供了高分辨率结构，并揭示了一些脂质的结合位点，这些脂质要么嵌入蛋白质内部，要么附着在蛋白质表面。这些脂质发挥着多种作用，包括辅因子的结合和结构支持的提供。文中还讨论了对诸如脂质、去污剂、小型两亲分子和离子等表面相关电子密度特征进行建模的挑战。
