NADH-ubiquinone reductase

NADH-ubiquinone reductase) and the second one was complex II (succinate-ubiquinone reductase). Chiesi and Schwaller [101] found that quercetin and tannin inhibited neuronal constitutive endothelial NO synthase. 

In the hydrogenosomal membranes, EPR spectra showed no trace of the highly characteristic features of the iron-sulfur clusters of complex I (NADH ubiquinone reductase) and the Rieske protein of complex III of the mitochondrial respiratory chain. This is consistent with the absence of... 

I NADH ubiquinone reductase 8 X 10 FMN, Fe-S protein NADH ubiquinol (QH2)... 

H. Ueno, H. Miyoshi, K. Ebisui, H. Iwamura, Comparison of the inhibitory action of natural rotenone and its stereoisomers with various NADH-ubiquinone reductases, Eur. J. Biochem. 225 (1994) 411-417. 

Ahammadsahib, K.I., Hollingworth, R.M., McGovren, P.J., Hui, Y.-H., and McLaughlin, J.L. Inhibition of NADH ubiquinone reductase (mitochondrial complex I) by bullatacin, a potent antitumor and pesticidal Annonaceous acetogenin. Life Sci., 53, 1113, 1993. 

Both the presence of methyl substituents in the tocopherols and their chromanol structures increase the ability of these compounds to form relatively stable radicals.498 499 This ability is doubtless probably important also in the function of ubiquinones and plastoquinones. Ubiquinone radicals (semiquinones) are probably intermediates in mitochondrial electron transport (Chapter 18) and radicals amounting to as much as 40% of the total ubiquinone in the NADH-ubiquinone reductase of heart mito-... 

Piericidins are the first compounds obtained by the screening search for insecticidal natural products among microbial metabolites.10 They were isolated from Streptomyces mobaraensis in 1963,11 and many piericidin derivatives have been found in microbial metabolites until now.12 Piericidins are not used as insecticides practically, but are important biological reagents because they have specific inhibitory activity toward the mitochondrial electron transport chain protein nicotinamide adenine dinucleotide (NADH)-ubiquinone reductase (complex I).13 Piericidin Ax (1 in Figure 1) is biosynthesized as a polyketide,14 but genes responsible for its biosynthesis are not yet identified. Total synthesis of piericidins A (1) was reported recently.15... 

Preparations of NADH dehydrogenase from mammalian mitochondria may be divided into three types (1) NADH-ubiquinone reductase or complex I of the electron transport system, (2) the high molecular weight NADH dehydrogenases, and (3) the low molecular weight NADH dehy-... 

NADH-ubiquinone reductase was isolated by Hatefi et al. in 1961 (27-B9). A procedure was developed for the resolution of the mitochondrial electron transport system into four enzyme complexes. Recently, a fifth fraction, which is capable of energy conservation and ATP-Pi exchange, was also isolated (30, 31). The overall scheme for the isolation of the five component enzyme complexes of the mitochondrial electron transport-oxidative phosphorylation system is given in Fig. 1. It is seen... 

The ubiquinone reductase activity of their low molecular weight dehydrogenase led Pharo et al. (64, 75) to conclude that the enzyme represented the mitochondrial NADH-ubiquinone reductase. However, it has been shown that the quinone reductase activity of the low molecular weight dehydrogenase is different from that of intact respiratory particles or complex I in many important respects, including kinetic constants, re-... 

As stated above, the low molecular weight NADH dehydrogenase of Pharo et al. (64) was considered incorrectly to be the NADH-ubiquinone reductase of the respiratory chain. This was in part because the ubiquinone reductase activity of the preparation could be partially inhibited by Amytal and by very low concentations of rotenone. It was demonstrated by others that these effects were different from the inhibitions... 

Weiss, H., and Leonard, K., 1987, Structure and function of mitochondrial ubiquinol cytochrome c reductase and NADH ubiquinone reductase, Chemica Scripta 27B 73n 81. 

NADH-ubiquinone reductase (EC 1.6.5.3) or Complex I is structurally by far the most complicated member of the respiratory chain. It is also the least known in terms of structure, electron transfer pathway or mechanism of proton translocation. Even the nomenclature of the isolated enzyme entities and of the FeS centres is problematic because it differs between research groups. 

Cadenas E, Boveris A, Ragan CI, Stoppani AOM (1977) Production of superoxide radicals and hydrogen peroxide by NADH-ubiquinone reductase and ubiquinol-cytochrome c reductase from beef heart mitochondria. Arch Biochem Biophys 180 248-257 Han D, Williams E, Cadenas E (2001) Mitochondrial respiratory chain-dependent generation of superoxide anion and its release to the intermebrane space. Biochem J 353 411-416... 

Piericidin Ai (37) has been isolated from Streplomyces sp., including S. mobaraensis and S. pactum [140,142], A potent insecticide [140], piericidin A inhibits mitochondrial electron transport through its action on NADH-ubiquinone reductase [146]. 

PG is made in mitochondria and microsomes of animal cells and appears to be primarily converted to DPG. DPG is biosynthesized exclusively on the matrix side of the mitochondrial inner membrane and is found only in this organelle. There is evidence that the rate-limiting step in DPG biosynthesis is the conversion of PA into CDP-DG (G.M. Hatch, 1994). Consistent with this idea, the levels of CTP regulate DPG biosynthesis in cardiac myoblasts (G.M. Hatch, 1996). Using techniques developed by Raetz and co-workers [14], a temperature-sensitive mutant of PG-P synthase in CHO cells was isolated (M. Nishijima 1993). The mutant had only 1% of wild-type PG-P synthase activity at 40°C and exhibited a temperature-sensitive defect in PG and DPG biosynthesis. This mutant was used to show that DPG is required for the NADH-ubiquinone reductase (complex I) activity of the respiratory chain. 

In benzoquinone-treated algae, the re-reduction rate of Cyt c could be accelerated by increasing the concentration of reduced DAD (not shown). In this case, addition of myxothiazol also blocked the reaction. Therefore, the inhibition caused by the treatment is not due to its impairing the b-c complex, but rather affects an upstream step, such as ubiquinone reduction. This was actually verified by Prof. R. Douce (personal communication), who found that p-benzoquinone was an inhibitor of the NADH-ubiquinone- reductase in isolated plant mitochondria. The slow re-reduction of Cyt c in Fig. 1 depends on the duration and concentration of the benzoquinone treatment, and as mentioned above, on the added reductant. In this experiment sufficient reduction occurs within each flashing period so that the saturation effect observed in the myxothiazol curve of Fig.2 does not occur. As shown in [l], under such conditions, the mitochondrial response remains linear. 

---