Cellular oxidation-reduction

Vanadium Compounds and Cellular Oxidation-Reduction Metabolism... 

The influences of vanadium on a variety of cellular oxidation-reduction reactions have been reported in many cells. In addition, similar types of interactions may occur in other experimental models in which redox properties are not monitored when vanadium is added to living cells or organisms. 

Cellular Oxidation-Reduction Reactions as Part of the Therapeutic Effect of Vanadium... 

Vanadium has marked influences on cellular growth, cellular oxidation-reduction, and enzyme function. The metal is part of the active site of some enzymes, widely believed to be a required ultra trace nutrient, and is toxic in large amounts. The development of vanadium complexes as therapeutic agents for diabetes and cancer is being actively pursued. Much of the influence of vanadium on biological processes... 

See Chapters 22 and 23 for the details of these energy-harvesting cellular oxidation-reduction reactions. 

In the first part of this book devoted to cellular metabolism, it was pointed out that riboflavin is converted to monophosphate and diphosphate, yielding the active coenzymes of a large number of enzymes involved in the cellular oxidation-reduction reaction. As can be expected, the enzyme activity for which these flavoproteins are responsible is decreased in riboflavin deficiency. This has been clearly demonstrated for amino acid oxidase. Extensive studies on the effect of riboflavin deficiency on a large number of proteins have not been carried out but it seems logical to assume that the clinicopathological changes that develop in riboflavin deficiency result from the reduced activity of the flavoprotein enzyme. Yet, many... 

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... 

NAD and NADP play a central role in energy metabolism, both being involved in many cellular oxidation reduction reactions. NAD functions in energy-producing reactions involving the catabolism of innumerable metabolites. NAD formed from oxidation reacts at the point of Complex I of the mitochondrial electron transport chain. Each mole of NADH consumed by the mitochondria furnishes energy for the formation of three moles of ATP. NADH is highly depleted in the cytosol. The phosphorylated dinucleotide. 

The ready reversibility of this reaction is essential to the role that qumones play in cellular respiration the process by which an organism uses molecular oxygen to convert Its food to carbon dioxide water and energy Electrons are not transferred directly from the substrate molecule to oxygen but instead are transferred by way of an electron trans port chain involving a succession of oxidation-reduction reactions A key component of this electron transport chain is the substance known as ubiquinone or coenzyme Q... 

Warburg and Christian showed that the color of this old yellow enzyme came from a flavin and proposed that its cyclic reduction and reoxidation played a role in cellular oxidation. When NADP+ was isolated the proposal was extended to encompass a respiratory chain. The two hydrogen carriers NADP+ and flavin would work in sequence to link dehydrogenation of glucose to the iron-containing catalyst that interacted with oxygen. While we still do not know the physiological function of the old yellow enzyme,b the concept of respiratory chain was correct. 

VANADIUM COMPOUNDS ON BIOLOGICAL SYSTEMS CELLULAR GROWTH, OXIDATION-REDUCTION PATHWAYS, AND ENZYMES... 

At first sight, the success of this method appeared to be due to the fact that (a) the medium used contained a wide range of metabolites known to occur in cellular metabolism, (b) the medium was continually flowing, so that worms were being continually exposed to new supplies of metabolites and at the same time the waste metabolic products were being continually swept away, (c) the gas phase was (apparently ) controlled, and (d) the oxidation-reduction potential was controlled, at least initially. 

The data of Table 11 compare the properties of certain non-heme iron proteins with ferredoxin. While there are certain similarities and differences between these proteins, it is stressed that the main feature which uniquely distinguishes ferredoxin from the others and from spectrally similar proteins from mammalian sources Kimura and Suzuki 60) Omura et al. (77)) is its low oxidation-reduction potential. This feature of ferredoxin renders it capable of fulfilling its recently recognized roles in cellular metabolism. These are dealt with in the final section of this chapter. 

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