Shahak Y, Crowther D, Hind G
Biochim Biophys Acta. 1981 Jul;636(2):234-43. doi: 10.1016/0005-2728(81)90097-9.
The sites of action, in spinach thylakoid, of known inhibitors of electron transport at the reducing end of photosystem I have been more accurately located by parallel investigation of effects on three partial reactions: photo-reduction (from water) of added NADP+, photoreduction of added cytochrome c, and dark reduction of cyto-chrome c by added NADPH. Comparison with inhibitory effects on cyclic electron flow (registered by the slow phase of the electrochromic response during repetitive flash excitation) permitted assessment of the role of ferredoxin and ferredoxin-NADP+ reductase (ferredoxin: NADP+ oxidoreductase, EC 1.18.1.3) in the cyclic electron transport pathway around photosystem I. Disulfodisalicylidenepropane-1,1-diamine inhibited all the above partial reactions except the ferredoxin-dependent photoreduction of cytochrome C. thereby indicating its interference with the reductase or the complexation between reductase and ferredoxin. Studies with purified ferredoxin-NADP+ reductase established it as the sensitive component. Cyclic flow is also sensitive to the above inhibitor and thus presumably involves the reductase. Supporting evidence for this came from studies of inhibition by substituted maleimides, which are inhibitors of electron transfer through the isolated reductase; these also inhibited the slow phase of the electrochromic response and all partial reactions except the photoreduction of cytochrome c. In contrast, an antiserum against the reductase affected only reactions involving NADP. The conclusion is drawn that the pathway of cyclic electron transport includes both ferredoxin and ferredoxin-NADP+ reductase, but not the NADP-binding site on the reductase.
通过对光系统I还原端电子传递已知抑制剂在菠菜类囊体中的作用位点进行平行研究，考察其对三个部分反应的影响，从而更精确地确定了这些位点：添加的NADP⁺的光还原（从水开始）、添加的细胞色素c的光还原以及添加的NADPH对细胞色素c的暗还原。将这些结果与对循环电子流的抑制作用（通过重复闪光激发期间电致变色响应的慢相记录）进行比较，从而评估了铁氧还蛋白和铁氧还蛋白-NADP⁺还原酶（铁氧还蛋白：NADP⁺氧化还原酶，EC 1.18.1.3）在光系统I周围循环电子传递途径中的作用。二磺基二水杨基亚丙基-1,1-二胺抑制了上述所有部分反应，但不包括依赖铁氧还蛋白的细胞色素c光还原反应，因此表明它干扰了还原酶或还原酶与铁氧还蛋白之间的络合。对纯化的铁氧还蛋白-NADP⁺还原酶的研究确定它是敏感成分。循环电子流也对上述抑制剂敏感，因此推测涉及还原酶。支持这一观点的证据来自对取代马来酰亚胺抑制作用的研究，取代马来酰亚胺是通过分离的还原酶进行电子传递的抑制剂；这些抑制剂也抑制了电致变色响应的慢相以及除细胞色素c光还原反应之外的所有部分反应。相比之下，针对还原酶的抗血清仅影响涉及NADP的反应。得出的结论是，循环电子传递途径包括铁氧还蛋白和铁氧还蛋白-NADP⁺还原酶，但不包括还原酶上的NADP结合位点。
