Forti G, Cappelletti A, Nobili R L, Garlaschi F M, Gerola P D, Jennings R C
Arch Biochem Biophys. 1983 Mar;221(2):507-13. doi: 10.1016/0003-9861(83)90169-8.
Ferredoxin-NADP reductase accounts for about 50% of the NADPH diaphorase activity of spinach leaf homogenates. The enzyme is bound to thylakoid membranes, but can be slowly extracted by aqueous buffers. Ferredoxin-NADP reductase can be extracted from the membranes by a 1- to 2-min treatment with a low concentration of trypsin. This treatment completely inactivates NADP photoreduction but does not affect electron transport from water to ferredoxin. It is shown that the inactivation is due to solubilization of ferredoxin-NADP reductase: the activity can be restored by addition of a very large excess of soluble enzyme in pure form. When ferredoxin-NADP reductase is added as a soluble enzyme after extraction or inactivation (by a specific antibody) of the membrane-bound enzyme, NADP photoreduction requires a very large excess of this enzyme, and the apparent Km for ferredoxin is also increased. These observations are discussed as related to the interactions of thylakoids with ferredoxin-NADP reductase.
铁氧化还原蛋白 - NADP还原酶约占菠菜叶匀浆中NADPH黄递酶活性的50%。该酶与类囊体膜结合，但可用水性缓冲液缓慢提取。用低浓度胰蛋白酶处理1至2分钟可从膜中提取铁氧化还原蛋白 - NADP还原酶。这种处理完全使NADP光还原失活，但不影响从水到铁氧化还原蛋白的电子传递。结果表明，失活是由于铁氧化还原蛋白 - NADP还原酶的溶解：通过添加非常大量的纯形式可溶性酶可恢复活性。当在提取或（通过特异性抗体）使膜结合酶失活后以可溶性酶形式添加铁氧化还原蛋白 - NADP还原酶时，NADP光还原需要非常大量的这种酶，并且铁氧化还原蛋白的表观Km也增加。讨论了这些观察结果与类囊体与铁氧化还原蛋白 - NADP还原酶相互作用的关系。
