Gadjieva R, Mamedov F, Albertsson PA
Department of Biochemistry, Center for Chemistry and Chemical Engineering, P.O. Box 124, University of Lund, S-221 00, Lund, Sweden.
Biochim Biophys Acta. 1999 Apr 21;1411(1):92-100. doi: 10.1016/s0005-2728(99)00010-9.
Thylakoids isolated from tobacco were fragmented by sonication and the vesicles so obtained were separated by partitioning in aqueous polymer two-phase systems. By this procedure, grana vesicles were separated from stroma exposed membrane vesicles. The latter vesicles could be further fractionated by countercurrent distribution, with dextran-polyethylene glycol phase systems, and divided into two main populations, tentatively named 'stroma lamellae' and 'end membrane'. Both these vesicle preparations have high chlorophyll a/b ratio, high photosystem (PS) I and low PS II content, suggesting their origin from stroma exposed regions of the thylakoid. The two vesicle populations have been compared with respect to biochemical composition and photosynthetic activity. The 'end membrane' has a higher chlorophyll a/b ratio (5.7 vs. 4.7), higher P700 content (4.7 vs. 3.3 mmol/mol of chlorophyll). The 'end membrane' has the lowest PS II content, the ratio PS I/PS II being more than 10, as shown by EPR measurements. The PS II in both fractions is of the beta-type. The decay of fluorescence is different for the two populations, the 'stroma lamellae' showing a very slow decay even in the presence of K3Fe(CN)6 as an acceptor. The two vesicle populations have very different surface properties: the end membranes prefer the upper phase much more than the stroma lamellae, a fact which was utilized for their separation. Arguments are presented which support the suggestion that the two vesicle populations originate from the grana end membranes and the stroma lamellae, respectively.
从烟草中分离出的类囊体通过超声破碎，所得囊泡通过在水性聚合物双相系统中分配进行分离。通过该程序，基粒囊泡与暴露于基质的膜囊泡分离。后一种囊泡可通过逆流分配，使用葡聚糖 - 聚乙二醇相系统进一步分级，并分为两个主要群体，暂定为“基质片层”和“内膜”。这两种囊泡制剂都具有高叶绿素a/b比、高光系统（PS）I和低PS II含量，表明它们起源于类囊体暴露于基质的区域。已对这两个囊泡群体的生化组成和光合活性进行了比较。“内膜”具有更高的叶绿素a/b比（5.7对4.7）、更高的P700含量（4.7对3.3 mmol/mol叶绿素）。如电子顺磁共振测量所示，“内膜”的PS II含量最低，PS I/PS II比值超过10。两个组分中的PS II均为β型。两种群体的荧光衰减不同，即使在存在作为受体的K3Fe(CN)6的情况下，“基质片层”的荧光衰减也非常缓慢。这两个囊泡群体具有非常不同的表面性质：内膜比基质片层更倾向于上层相，这一事实被用于它们的分离。文中提出了一些论据，支持这两个囊泡群体分别起源于基粒内膜和基质片层的观点。
