NAD P H Oxidases

During the last decades, several NOXs have been purified from various microbial strains belonging to the genera Streptococcus [50-52], Lactobacillus [49, 53, 54], Methanocaldococcus [55], Brevibacterium [56], Eubacterium [57], Thermococcus [48, 58-60], Archaeo bus [61], and Clostridium [62]. In particular, NOXs purified from thermophilic microorganisms are of interest because they are very stable biocatalysts, which enable biotransformations to be operated at high temperature and at increased reaction rates [48]. 

Organism opt rc) PH pt Substrate Main product (NADH, pM) of Oj reduction References 

Most of the NOXs described in the Hterature selectively oxidize NADH, whereas only few enzymes are able to oxidize both NADH and NADPH, such as the oxidases produced by Therrmcoccus kodakarensis [48], Lactobacillus sanfranciscensis [49], or Thermococcus profundus [58]. In any case, the specific activity for NADH is always much higher than the one for NADPH. 

The exploitation of NOXs for nicotinamide cofactor regeneration in synthetic applications has been described in several papers. 

The first reported examples concern the oxidation of NADH catalyzed by the NOX from L. brevis and I. sanfranciscensis [53, 64], which were coupled to the enantioselective oxidation of DL-leucine catalyzed by t-leudne dehydrogenase and to the oxidation of L-glutamate to a-ketoglutarate catalyzed by L-glutamate dehydrogenase, respectively. Unfortunately, these two NOXs showed a low suitabihty for a wider application on preparative scale because of product inhibition and a Hmited stability under operative conditions [1, 64, 65]. 

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It is possible that dietary flavonoids participate in the regulation of cellular function independent of their antioxidant properties. Other non-antioxidant direct effects reported include inhibition of prooxidant enzymes (xanthine oxidase, NAD(P)H oxidase, lipoxygenases), induction of antioxidant enzymes (superoxide dismutase, gluthathione peroxidase, glutathione S-transferase), and inhibition of redox-sensitive transcription factors. 

NAD(P)H oxidase can also be activated by fluid shear stresses. This is one reason why branched and curved arteries tend to develop atherosclerotic plaques earlier than straight arteries. Using a spin probe to detect 02 , Hwang et al. have demonstrated that monolayer cultures of EC exposed to oscillatory (but not laminar) shear stresses produce the radical using NAD(P)H oxidase.292 A subsequent study showed that XO also responds to oscillatory shear stress.293 Other workers, using BMPO, have detected the flow-induced production of 02 by mitochondria.294... 

Figure 2-9. Formation of H202 through the concerted action of NAD(P)H oxidase and CuZn-superoxide dismutase, as proposed by Ogawa et al. (1997).

Guzik TJ, West NE, Black E, McDonald D, Ratnatunga C, Pillai R, Channon KM. 2000. Vascular superoxide production by NAD(P)H oxidase Association with endothelial dysfunction and clinical risk factors. Circ Res 86 E85-90. 

In fact, the a-ketoglutarate/glutamate dehydrogenase is a generally applicable method for the regeneration of NAD and NADP in laboratory scale productions. Both components involved are inexpensive and stable. Quite recently, a method for the oxidation of the reduced nicotinamide coenzymes based on bacterial NAD(P)H oxidase has been described [225], This enzyme oxidizes NADH as well as NADPH with low Km values. The product of this reaction is peroxide, which tends to deactivate enzymes, but it can be destroyed simultaneously by addition of catalase. The irreversible peroxide/catalase reaction favours the ADH catalyzed oxidation reaction, and complete conversions of this reaction type are described. 

G8. Greiber, S., Munzel, T., Kastner, S., Muller, B., Schollmeyer, P., and Pavenstadt, H., NAD(P)H oxidase activity in cultured human podocytes Effects of adenosine triphosphate. Kidney Int. 53, 654-663 (1998). 

Inhibits Ca2+ conductances Activates PLC, PC-PLC, and PLA2 Activates/inhibits NOS Activates NAD(P)H oxidase Activates NHE-1... 

Mukhin YV, Gamovskaya MN, Collinsworth G, et al. 5-Hydroxytryptamine1A rcccptor/G stimulates mitogen-activated protein kinase via NAD(P)H oxidase and reactive oxygen species upstream of src in Chinese hamster ovary fibroblasts. Biochem J 2000 347(Pt l) 61-67. 

Griendling, K. K., Sorescu, D., and Ushio-Fukai, M. 2000. NAD(P)H oxidase role in cardiovascular biology and disease. Circ Res 86 494-501. 

Zuo, L., Ushio-Fukai, M., Ikeda, S., et al. 2005. Caveolin-1 is essential for activation of Racl and NAD(P)H oxidase after angiotensin II type 1 receptor stimulation in vascular smooth muscle cells role in redox signaling and vascular hypertrophy. Arterioscler Thromb Vase Biol 25 1824-1830. 

Cruzado, M. C., Risler, N. R., Miatello, R. M., Yao, G., Schiffrin, E. L., and Touyz, R. M. 2005. Vascular smooth muscle cell NAD(P)H oxidase activity during the development of hypertension effect of angiotensin II and role of insulinhke growth factor-1 receptor transactivation. Am. J. Hypertens. 18 81-87. 

Inoguchi, T., and H. Nawata. 2005. NAD(P)H oxidase activation a potential target mechanism for diabetic vascular complications, progressive beta-cell dysfunction and metabolic syndrome. Curr. Drug Targets. 6 495-501. 

Inoguchi, T., P. Li, F. Umeda, H.Y. Yu, M. Kakimoto, M. Imamura, T. Aoki, T. Etoh, T. Hashimoto, M. Naruse, H. Sano, H. Utsumi, and H. Nawata. 2000. High glucose level and free fatty acid stimulate reactive oxygen species production through protein kinase C-dependent activation of NAD(P)H oxidase in cultured vascular cells. Diabetes 49 1939-1945. 

Inoguchi, T., T. Sonta, H. Tsubouchi, T. Etoh, M. Kakimoto, N. Sonoda, N. Sato, N. Sekiguchi, K. Kobayashi, H. Sumimoto, H. Utsumi, and H. Nawata. 2003. Protein kinase C-dependent increase in reactive oxygen species (ROS) production in vascular tissues of diabetes role of vascular NAD(P)H oxidase. J. Am. Soc. Nephrol. 14 S227-S232. 

Inhibits NAD(P)H oxidase cytochrome b558 activity, increases oxidant production by the mitochondria and inhibits ASMC proliferation and phosphorylation of the ERK1/2 mitogen-activated protein kinase and expression of cyclin D1 in human airway smooth muscle [74]... 

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