Maximychev A V, Kostyuchenko I G, Chibirova F Kh, Zhilinskaya E A, Chekulaeva L N, Timashev S F
Karpov Physico-Chemical Research Institute, Moscow.
Membr Cell Biol. 1997;10(5):487-501.
Purple membranes (PM) from Halobacterium were reconstituted with 57Fe ions and investigated by Mössbauer spectroscopy within the temperature range from 5 to 300 K at the Fe/bacteriorhodopsin (BR) ratio 0.6-300. When the Fe/Br ratio was below 2, Fe3+ bonded to PM mostly as hydroxymonomeric particle [FeOH]2+.5H2O, the apparent charge of the iron ion being two. When the Fe/BR ratio exceeded two, the dimeric form FeOH4.8H2O along with a cluster form dominated. The temperature dependences of the mean square displacement show that the mobility of Fe ions changes from the solid-state type to the quasi-diffusional one at temperatures approximately 200 and approximately 230 K for the dimeric or monomeric and cluster iron forms, respectively. The nature of the cation binding sites and their location on the PM surface are discussed. A possible role of the divalent cation binding to PM in the mechanism of BR proton pumping is suggested.
用57Fe离子对嗜盐菌的紫膜（PM）进行了重组，并在5至300K的温度范围内，以0.6 - 300的铁/细菌视紫红质（BR）比率通过穆斯堡尔光谱进行了研究。当铁/BR比率低于2时，Fe3+主要以羟基单体颗粒[FeOH]2+.5H2O的形式与PM结合，铁离子的表观电荷为2。当铁/BR比率超过2时，二聚体形式FeOH4.8H2O与簇状形式占主导。均方位移的温度依赖性表明，对于二聚体或单体及簇状铁形式，Fe离子的迁移率分别在约200K和约230K时从固态类型转变为准扩散类型。讨论了阳离子结合位点的性质及其在PM表面的位置。提出了二价阳离子与PM结合在BR质子泵浦机制中的可能作用。
