菌紫质研究的新进展

New Progress in The Study of Bacteriorhodopsin

菌紫质（ＢＲ）是嗜盐菌紫膜中的唯一蛋白质，野生型的ＢＲ分子含有２４８个氨基酸残基，其中一个视黄醛通过希夫碱基连结在第２１６位赖氨酸上，它具有质子泵的功能．光照下，ＢＲ进行光循环，光循环又与质子泵过程相关联．菌紫质的结构和功能方面的研究已有很大进展，但其光循环途径和质子泵的机理还不太清楚．文章概述了近年来对菌紫质结构，光循环和质子泵机理研究的进展，尤其对７争论较大的菌紫质光循环途径的四类模型作了较详细的介绍．

Bacteriorhodopsin (BR) is the onlyprotein in the purple membrane (PM) fromHalobacterium halobium. Wild-type BR contains a single-chain polypeptide of 248 aminoacidresidues and a retinal attached to Lys216 of thepeptide via a schiff base, BR has the function ofproton pump, Upon illumination, BR goesthrough a photocycle which is considered to becorrelated with its proton pumping process. Thegood progress has been made in the studay of thestructure and function of BR, but the path ofphotocycle and mechanism of proton pump arestill not clear. The progress of the structure,photocycle and proton pump of BR in recentyears are briefly introduced. And the four models of the path of photocycle which are in greatargument are discussed in detail.