Iwasaki Y, Ishikawa H, Hibino T, Takabe T
Department of Chemistry, Meijo University, Nagoya, Japan.
Biochim Biophys Acta. 1991 Aug 23;1059(2):141-8. doi: 10.1016/s0005-2728(05)80198-7.
N-terminal amino acid sequencing was carried out to characterize the genes of the cucumber PS I complex (PSI-100) that contains eight polypeptides and catalyzes the light-dependent transfer of electrons from plastocyanin to ferredoxin. The genes of all subunits except the 17.5 kDa polypeptide in PSI-100 have been identified. These are psaA/psaB (65/63 kDa), psaD (20 kDa), psaE (19.5 kDa), psaF (18.5 kDa), psaH (7.6 kDa), and psaC (5.8 kDa). The 17.5 kDa polypeptide is a new protein and is designated tentatively as the gene product of psaM. N-terminal amino-acid sequencing indicated the presence of two polypeptides in the 7.6 kDa band. One of these is the gene product of psaH and is essential for the activity of the PS I complex, and the other one is as yet unrecognized and largely depleted in the PSI-100 complex. Gene products of psaG, psaI, and psaK, which have been proposed as the components of PS I complex, are not involved in the PSI-100 complex, but are involved in the PS I complex (PSI-200), which contains 120 chlorophyll per reaction center chlorophyll (P700) and light-harvesting chlorophyll a/b protein complexes. Three polypeptides (26,23 and 22.5 kDa) are not involved in the PSI-100 and are assigned as the apo-protein of light-harvesting chlorophyll a/b protein complexes.
对黄瓜光系统I复合体（PSI - 100）的基因进行了N端氨基酸测序，该复合体包含8种多肽，催化从质体蓝素到铁氧化还原蛋白的光依赖电子转移。除PSI - 100中17.5 kDa多肽外，所有亚基的基因均已被鉴定。这些基因是psaA/psaB（65/63 kDa）、psaD（20 kDa）、psaE（19.5 kDa）、psaF（18.5 kDa）、psaH（7.6 kDa）和psaC（5.8 kDa）。17.5 kDa多肽是一种新蛋白质，暂定为psaM的基因产物。N端氨基酸测序表明在7.6 kDa条带中存在两种多肽。其中一种是psaH的基因产物，对光系统I复合体的活性至关重要，另一种尚未被识别，且在PSI - 100复合体中大量缺失。已被提议作为光系统I复合体组分的psaG、psaI和psaK的基因产物不参与PSI - 100复合体，但参与光系统I复合体（PSI - 200），该复合体每个反应中心叶绿素（P700）含有120个叶绿素以及捕光叶绿素a/b蛋白复合体。三种多肽（26、23和22.5 kDa）不参与PSI - 100，被指定为捕光叶绿素a/b蛋白复合体的脱辅基蛋白。
