Orlando J A, Sabo D, Curnyn C
Department of Biology, Boston College, Chestnut Hill 67, Massachusetts.
Plant Physiol. 1966 Jun;41(6):937-45. doi: 10.1104/pp.41.6.937.
We have investigated the photoreduction of pyridine nucleotides by crude extracts and chromatophores of Rhodopseudomonas spheroides.Our findings are as follows:NADP is preferentially photoreduced by crude extracts (37,000 x g supernatant fraction) and there is no requirement for the addition of exogenous substrates. Crude extracts also catalyze a nonphotosensitive reduction of NAD.NADP photoreduction is completely inhibited if an NADH trapping system is present and indicates that NADH is required for NADP photoreduction.Washed chromatophores (150,000 x g pellet) do not catalyze NADP photoreduction unless the supernatant fraction is added. The restoring effect of supernatant fraction is lost upon boiling and dialysis. However, supernatant materials can be replaced by an NADH generating system. There is no requirement for anaerobic conditions.Evidence has been presented which suggests that Rhodopseudomonas spheroides contains an energy-linked transhydrogenase that can be driven by a high energy intermediate generated by light or ATP. This intermediate may also be functional in ATP synthesis. The synthesis of ATP and the ATP-supported transhydrogenase is inhibited by oligomycin. This inhibitor does not affect the light-mediated reaction.
我们研究了球形红假单胞菌的粗提取物和载色体对吡啶核苷酸的光还原作用。我们的研究结果如下：粗提取物（37,000×g上清液部分）优先光还原NADP，且无需添加外源底物。粗提取物还催化NAD的非光敏还原。如果存在NADH捕获系统，NADP光还原会被完全抑制，这表明NADP光还原需要NADH。洗涤后的载色体（150,000×g沉淀）不会催化NADP光还原，除非添加上清液部分。上清液部分的恢复作用在煮沸和透析后会丧失。然而，上清液物质可以被NADH生成系统替代。不需要厌氧条件。已有证据表明，球形红假单胞菌含有一种能量偶联转氢酶，它可以由光或ATP产生的高能中间体驱动。这种中间体在ATP合成中可能也有作用。ATP的合成以及ATP支持的转氢酶受到寡霉素的抑制。这种抑制剂不影响光介导的反应。
