Nicotinamide adenine dinucleotide cellular reaction

In view of the oxidant nature of ozone, a number of investigators have evaluated its effects on intracellular compounds that are normally active in cellular redox reactions. Attention has focused particularly on reduced pyridine nucleotides—reduced nicotinamide adenine dinudeotide (NADH) and reduced nicotinamide adenine dinucleotide phosphate (NADPH)— and on sulfhydryl compounds, specifically reduced glutathione (GSH). 

Niacin, also known as vitamin B3, nicotinic acid or vitamin PP, is a water-soluble B-complex vitamin (Table 7.1). This vitamin is the generic descriptor for two vitamers niacin and niacinamide. In the research literature the terms nicotinic acid/nicotinamide are most commonly used, while in medical practice niacin/niadnamide are preferred. The vitamin is obtained from the diet in the form of nicotinic acid, nicotinamide and tryptophan, which are transformed to nicotinamide adenine dinucleotides, NAD and NADP. These compounds participate in cellular oxidation-reduction reactions that are critical for energy production. NAD and NADP also participate in a wide variety of... 

Inhibition by niacin of inflammatory and oxidative pathways may exert anti-atherosclerotic effects. In cultured human aortic endothelial cells, niacin increased cellular levels of nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) and glutathione, regulators of redox reactions, and reduced production of reactive oxygen species. Niacin inhibited monocyte adhesion through the inhibition of tumour necrosis factor-alpha (TNF-a) induced expression of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) (Ganji et al. 2009). Persistent increases in plasma adiponectin, an adipokine with anti-inflammatory properties, were found after 6 months of niacin treatment in humans (Linke et al. 2009). 

There are, however, many enzymes which, because they do not seem to be contained in such cellular particles, are referred to as soluble enzymes . Thus, the chemical reactions whereby the yeast cell converts glucose into ethanol and which seem to be identical with the first sequence of reactions in the normal respiration of plant cells are catalysed by such soluble enzymes. In the living cell such enzymes may, however, function as an organised multi-enzyme system which forms part of the endoplasmic reticulum. The fact that they cannot be obtained in association may merely reflect our inability to preserve the endoplasmic reticulum in cell-free preparations. Thus, in alcoholic fermentation by the yeast cell, which occurs in the absence of oxygen, there is an oxidative reaction which is balanced by a reduction. These both involve dehydrogenase enzymes having the same co-enzyme, nicotinamide adenine dinucleotide. One of these reactions, that catalysed by alcohol dehydrogenase, has already been mentioned (p. 73, eqn. 6). The other reaction... 

Two coenzymes which are involved in most of the redox reactions of metabolism are nicotine adenine dinucleotide, NAD", and FAD, flavine adenine dinucleotide. Most metabolic oxidations are, in fact, dehydrogenations, and not reactions with oxygen. Nicotinamide is derived from nicotinic acid, and the isoalloxazine ring of FAD is derived from riboflavin. Thiamin is the principal cofactor in enzymatic decarboxylations. Many of the vitamins serve as coenzymes in a wide variety of cellular reactions. 

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