细菌视紫红质的质子传输机理

Molecular Mechanism for Proton Translocation of Bacteriorhodopsin

菌视紫红质 (bR)是嗜盐菌紫膜中的唯一蛋白质成分 ,具有质子泵、电荷分离和光致变色功能 .bR分子中的发色团视黄醛通过质子化席夫碱以共价键与Lys2 16相连 .bR分子受可见光照射后 ,视黄醛发生从全 反到13 顺式构型的异构化 ,导致席夫碱的去质子化 ,继之以可极化基团位置的改变 .力场的变化引起包括蛋白质三级结构在内的诸多变化 ,这些变化促进并保证了质子从细胞质侧向细胞外侧的定向传输 .

Bacteriorhodopsin (bR) is the sole protein in the purple membrane of Halobacterium salinarium, which functions as proton pump, charge separation and photochromism. The chromophore retinal is covalently attached to Lys 216 via a protonated Schiff base. Upon illumination, the all-trans to 13-cis isomerization of the retinal results in deprotonation of the Schiff base followed by alterations in protonatable groups within bacteriorhodopsin. The changed force field induces changes, even in the tertiary structure, which facilitate and warrant the vectorial proton translocation.