Djavadi F H, Moradi M, Djavadi-Ohaniance L
Eur J Biochem. 1980 Jun;107(2):501-4. doi: 10.1111/j.1432-1033.1980.tb06056.x.
It has been accepted that in Saccharomyces cerevisiae submitochondrial particles do not oxidize the NADPH and that the NADPH:cytochrome c reductase is not a mitochondrial enzyme but rather a microsomal one. The present study provides clear evidence that in S. cerevisiae a direct oxidation of NADPH occurs through the mitochondrial electron transport system. The following results wee obtained: submitochondrial particles from S. cerevisiae are capable of oxidizing NADPH with a relatively high rate. The oxidation of NADPH is sensitive to antimycin A and NaN3 but insensitive to rotenone as is known for NADPH oxidation. Also NADPH:cytochrome c reductase activity is inhibited by antimycin A. NADPH-induced reduction of cytochromes b, c + c1, and aa3 is as fast as NADPH-induced reduction. Cytochromes are reduced to the same extent with either NADH or NADPH. The changes of the ratio of NADH/NADPH oxidation rate and the ratio of NADH K3Fe(CN)6/NADPH-K3Fe(CN)6 reductase activities at various phases of growth suggest that two distinct pyridine nucleotide dehydrogenases could be responsible for NADH and NADPH oxidation. This problem remains to be elucidated.
人们已经公认，在酿酒酵母中，亚线粒体颗粒不氧化NADPH，并且NADPH：细胞色素c还原酶不是线粒体酶，而是微粒体酶。本研究提供了明确的证据，表明在酿酒酵母中，NADPH通过线粒体电子传递系统直接氧化。获得了以下结果：酿酒酵母的亚线粒体颗粒能够以相对较高的速率氧化NADPH。NADPH的氧化对抗霉素A和NaN3敏感，但对鱼藤酮不敏感，这与已知的NADPH氧化情况相同。此外，NADPH：细胞色素c还原酶活性也被抗霉素A抑制。NADPH诱导的细胞色素b、c + c1和aa3的还原与NADPH诱导的还原一样快。细胞色素被NADH或NADPH还原到相同程度。在生长的各个阶段，NADH/NADPH氧化速率的比值以及NADH-K3Fe(CN)6/NADPH-K3Fe(CN)6还原酶活性的比值变化表明，可能有两种不同的吡啶核苷酸脱氢酶负责NADH和NADPH的氧化。这个问题仍有待阐明。
