Klausner R D, Berman M, Blumenthal R, Weinstein J N, Caplan S R
Biochemistry. 1982 Jul 20;21(15):3643-50. doi: 10.1021/bi00258a018.
Purified bacteriorhodopsin from purple membrane sheets isolated from Halobacter halobium was solubilized with a bile salt detergent, 3-[(3-cholamidopropyl) dimethyl-ammonium]-1-propanesulfonate (CHAPS). The detergent-solubilized protein was then incorporated into lecithin vesicles at either high (450:1) or low (65:1) lipid to protein ratios. Circular dichroism studies showed that the bacteriorhodopsin incorporated was in a monomeric form in the 450:1 vesicles. The 65:1 vesicles exhibited an exciton splitting characteristic of the aggregated state of bacteriorhodopsin. We then examined the light-induced movement of protons for these two preparations. Compartmental analysis was used to derive a kinetic model for the observed proton movement. The pumping was qualitatively the same for monomeric and aggregated protein. A three-compartment model provided an excellent description of proton movement in both sets of vesicles and at four different light intensities. This model demands two independent processes to account for the proton movement. The rate coefficients for both are linearly related to light intensity. However, the total flux of protons via one of these processes diminishes as a function of the hydrogen ion accumulation within the vesicles.
从盐生盐杆菌中分离出的紫色膜片中纯化得到的细菌视紫红质，用胆盐去污剂3-[(3-胆酰胺丙基)二甲基铵]-1-丙烷磺酸盐（CHAPS）进行增溶。然后将去污剂增溶的蛋白质以高（450:1）或低（65:1）的脂质与蛋白质比例掺入卵磷脂囊泡中。圆二色性研究表明，掺入的细菌视紫红质在450:1的囊泡中呈单体形式。65:1的囊泡表现出细菌视紫红质聚集状态的激子分裂特征。然后我们研究了这两种制剂中光诱导的质子运动。采用区室分析来推导观察到的质子运动的动力学模型。单体和聚集蛋白的质子泵浦在定性上是相同的。三室模型对两组囊泡中以及四种不同光强度下的质子运动都提供了很好的描述。该模型需要两个独立的过程来解释质子运动。两者的速率系数都与光强度呈线性关系。然而，通过这些过程之一的质子总通量会随着囊泡内氢离子积累而减少。
