Kozuleva M A, Naĭdov I A, Mubarakshina M M, Ivanov B N
Biofizika. 2007 Jul-Aug;52(4):650-5.
Oxygen reduction in a photosynthetic electron-transport chain (PETC) was studied in isolated pea thylakoids in the presence of either ferredoxin, or ferredoxin + NADP+, or cytochrome c. The contribution of the electron flow through ferredoxin to the total oxygen reduction was evaluated by comparing the rate of oxygen reduction and the rate of oxidation of reduced ferredoxin in the light. It was found that at ferredoxin concentrations optimal for NADP+ reduction, 30-50% of electrons transferred to oxygen went through ferredoxin both in the absence and presence of NADP+. However, the absolute rate of oxygen reduction by membrane components of PETC in the presence of NADP+ was 3-4 times less than that in the presence of ferredoxin alone and close to the rate of oxygen reduction in the presence of cytochrome c. It was assumed that a Photosystem I component, whose role in this process depends on the rate of electron outflow from terminal acceptors of this photosystem, participates in oxygen reduction, and this component is phylloquinone.
在分离的豌豆类囊体中，分别在存在铁氧还蛋白、铁氧还蛋白 + NADP⁺ 或细胞色素 c 的情况下，研究了光合电子传递链（PETC）中的氧还原。通过比较光下氧还原速率和还原型铁氧还蛋白的氧化速率，评估了通过铁氧还蛋白的电子流对总氧还原的贡献。结果发现，在对NADP⁺ 还原而言最适宜的铁氧还蛋白浓度下，无论有无NADP⁺，转移到氧的电子中有30 - 50% 通过铁氧还蛋白。然而，在存在NADP⁺ 时，PETC膜成分的绝对氧还原速率比仅存在铁氧还蛋白时低3 - 4倍，且接近存在细胞色素 c 时的氧还原速率。据推测，一个光合系统I成分参与了氧还原，其在此过程中的作用取决于该光合系统末端受体的电子流出速率，该成分是质体醌。
