Hellingwerf K J
J Bioenerg Biomembr. 1987 Jun;19(3):203-23. doi: 10.1007/BF00762413.
Reaction centers (RCs) from Rhodopseudomonas sphaeroides were reconstituted into asolectin vesicles by cosonication. Equilibrium centrifugation on sucrose gradients showed that the vesicles were homogeneous in density (i.e., lipid-to-protein ratio) when reconstituted at a molar lipid-to-protein ratio between 500 to 1000. At lower ratios, a considerable fraction of RCs was not incorporated into closed vesicles, while at higher ratios, an increasing population of liposomes was protein-free. The average vesicle size decreased with increasing lipid-to-protein ratio, exhibiting considerable size heterogeneity within a sample. The average diameter of the largest and smallest population of vesicles, reconstituted at a molar lipid-to-protein ratio of 560, was 1200 and 400 nm, respectively. The orientation of reconstituted RCs with respect to the plane of the membrane was determined from the flash-induced rereduction kinetics of the special-pair bacteriochlorophyll dimer in the presence of reduced cytochrome c. The predominant orientation of RCs was such that the cytochrome c binding sites faced the external medium. The net orientation of RCs in reconstituted vesicles decreased with vesicle size and was strongly influenced by the ionic strength during reconstitution.
通过共超声处理将来自球形红假单胞菌的反应中心（RCs）重组到大豆卵磷脂囊泡中。在蔗糖梯度上进行平衡离心表明，当以500至1000的摩尔脂-蛋白比进行重组时，囊泡在密度（即脂-蛋白比）上是均匀的。在较低比例下，相当一部分RCs未掺入封闭的囊泡中，而在较高比例下，无蛋白脂质体的数量不断增加。平均囊泡大小随脂-蛋白比的增加而减小，在样品中表现出相当大的大小异质性。以560的摩尔脂-蛋白比重组的最大和最小囊泡群体的平均直径分别为1200和400nm。在还原型细胞色素c存在的情况下，根据闪光诱导的特殊对细菌叶绿素二聚体的再还原动力学来确定重组RCs相对于膜平面的方向。RCs的主要方向是细胞色素c结合位点面向外部介质。重组囊泡中RCs的净方向随囊泡大小而降低，并在重组过程中受到离子强度的强烈影响。
