Nicotinic acid requirement

Although only monovalent anions are included in Table 6.8, similar effects are observed with some divalent anions. Salicylic acid will elute sulfate in 5.2 min and thiosulfate in 7.3 min under the conditions in Table 6.7. However, the weaker eluents such as succinic or nicotinic acid require an excessive amount of time to elute divalent anions. 

The conversion of nicotinamide to nicotinic acid requires the activities of a deaminase and a ribonucleotide pyrophosphorylase. Although a detailed description of mechanisms controlling NAD coenzyme synthesis in mammalian tissues is not available, it has been suggested that the regulatory restraints are... 

Evidence that 3-hydroxyanthranilic acid was a precursor of nicotinic acid was obtained from the observations of Mitchell and Nyc (61) that the compound could replace the nicotinic acid requirements of some Neurospora mutants. Bonner (62) has isolated a mutant which spedfi[Pg.634]

Volcani and Snell (73) have reported that k3rnurenine and hydroxyanthranilic acid do not replace the nicotinic acid requirements for microorganisms such as Lactobacillus arabinosus, Leucomstoc mesenteroides, Streptococcus faecalis, and Proteus vulgaris. Earlier reports that ornithine and tryptophan could serve as precursors of nicotinic acid in Escherichia coli do not appear to have been substantiated, and there is no positive evidence at present supporting the view that the tryptophan pathway operates in this organism. Yanofsky (H, 15) was unable to demonstrate that tryptophan and ornithine intermediates could replace nicotinic acid in mutants of E. coli and Bacillus subtilis. Furthermore, it was found that C -tryptophan was not converted to nicotinic acid in these mutants. 

Most foods of animal origin contain nicotinamide in the coenzyme form (high bioavialability). Liver and meat are particularly rich in highly bioavailable niacin. Most of the niacin in plants, however, occurs as nicotinic acid in overall lower concentrations and with a lower bioavailability. The major portion of niacin in cereals is found in the outer layer and its bioavailability is as low as 30% because it is bound to protein (niacytin). If the diet contains a surplus of L-tryptophan (Ttp), e.g., more than is necessary for protein synthesis, the liver can synthesize NAD from Trp. Niacin requirements are therefore declared as niacin equivalents (1 NE = 1 mg niacin = 60 mg Trp). 

Nicotinic acid has been used to treat hyperlipidemia when of the order of 1—6 g/d are required, causing dilation of blood vessels and flushing, with skin irritation. Intakes of both nicotinic acid and nicotinamide in excess of 500 mg/d can cause liver damage. 

Vitamin Ba (pyridoxine, pyridoxal, pyridoxamine) like nicotinic acid is a pyridine derivative. Its phosphorylated form is the coenzyme in enzymes that decarboxylate amino acids, e.g., tyrosine, arginine, glycine, glutamic acid, and dihydroxyphenylalanine. Vitamin B participates as coenzyme in various transaminations. It also functions in the conversion of tryptophan to nicotinic acid and amide. It is generally concerned with protein metabolism, e.g., the vitamin B8 requirement is increased in rats during increased protein intake. Vitamin B6 is also involved in the formation of unsaturated fatty acids. 

The usable range for T. pyriformis is from 0.3-300 mug/ml. The organism utilizes pyridoxal, pyridoxamine pyridoxine, and pyridoxal-5-phosphate. Pyridoxamine + pyridoxal yielded the best growth approximately 120 times more pyridoxine is required to yield the same growth as pyridoxamine (Fig. 4). As with nicotinic acid and its amide, when these compounds are added together in the same concentration, the increment of growth is less than the sum of the individual increments. Upon an intramuscular load dose of 100 mg of pyridoxine, peak vitamin Bs levels are reached 2 hours after injection. The curves for 4 normal individuals are illustrated in Fig. 5. 

Group-transfer reactions often involve vitamins3, which humans need to have in then-diet, since we are incapable of realizing their synthesis. These include nicotinamide (derived from the vitamin nicotinic acid) and riboflavin (vitamin B2) derivatives, required for electron transfer reactions, biotin for the transfer of C02, pantothenate for acyl group transfer, thiamine (vitamin as thiamine pyrophosphate) for transfer of aldehyde groups and folic acid (as tetrahydrofolate) for exchange of one-carbon fragments. Lipoic acid (not a vitamin) is both an acyl and an electron carrier. In addition, vitamins such as pyridoxine (vitamin B6, as pyridoxal phosphate), vitamin B12 and vitamin C (ascorbic acid) participate as cofactors in an important number of metabolic reactions. 

In the form in which they are consumed, many vitamins are not biologically active. For several water-soluble vitamins such as thiamine, riboflavin, nicotinic acid, pyridoxine, activation includes phosphorylation or, as is the case with riboflavin and nicotinic acid, coupling to purine or pyridine nucleotides is required. In their major known actions, water-soluble vitamins participate as cofactors for specific enzymes, whereas at least two fat-soluble... 

Achromobacter xylosoxydans has been used to cany out the selective hydroxylation in high yield, using the enzyme which catalyses the first step in nicotinic acid degradation. The whole-cell biotransformation process has been scaled-up to 12 m, which is sufficient to produce high purity 6-hydroxynicotinic acid for the subsequent chemical reactions. The hydroxylation is oxygen requiring, so that oxygen transfer rate-limits the reaction. 

Potatoes are an excellent source of carbohydrates and contain significant amounts ofphosphorus, potassium, calcium, and vitamins, especially vitamin C. Potato protein content, at over 10%, is relatively close to that of wheat flour (11%) also, thanks to their lysine, methionine, cystine and cysteine contents, potatoes are a valuable supplement to cereal proteins. For instance, potatoes provide a significant source of proteins (10-15% of total requirements), a major source of vitamin C, an important source of energy, and also minerals like iron and other vitamins such as thiamin, nicotinic acid, riboflavin, and pro-vitamin A (p carotene) (Salunkhe and Kadam, 1991). 

The daily requirement for an adult is about 7.5 mg. The amount is decreased by the presence in the diet of tryptophan, which can be converted partially to nicotinic acid (Chapter 25).d e Tryptophan is about 1 /60 as active as nicotinic acid itself. The one-time prevalence of pellagra in the southern United States was a direct consequence of a diet high in maize whose proteins have an unusually low tryptophan content. 

Niacm - piTAMINS - NIACINE,NICOTINAMIDEAND NICOTINIC ACID] (Vol 25) - [FEEDS AND FEED ADDITIVES - PET FOODS] (Vol 10) - [FINECHEMICALS - PRODUCTION] (Vol 10) - [FEEDS AND FEED ADDITIVES - RUMINANT FEEDS] (Vol 10) -m dairy substitutes pAIRY SUBSTITUTES] (Vol 7) -m dairy substitutes pAIRY SUBSTITUTES] (Vol 7) -deficiency of piTAMINS - NIACINE,NICOTINAMIDEAND NICOTINIC ACID] (Vol 25) -dietary requirements piTAMINS - NIACINE, NICOTINAMIDE AND NICOTINIC ACID] (Vol 25) -m nuts PUTS] (Vol 17) -m nuts PUTS] (Vol 17)... 

Nicotinamide extraction requires more specialized conditions than nicotinic acid due to its relative instability. Aqueous extractants and dilute sulphuric or hydrochloric acid have been used to release the vitamers from the food matrix without degrading nicotinamide (9,44). 

Currently, a wide range of reactive dyes of varying constitution is available which are suitable for many different applications [33], [6, p. 510-516], In most cases, dye is fixed to the substrate under alkaline conditions. However, dyes with phos-phonate groups are applied in an acid dyeing bath, and quaternary nicotinic acid derivatives require neutral conditions. These dyes are used mainly for dyeing PES-CEL blends. 

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