Nicotinamide erythrocytes

Morita Y, Sakai T, Araki S, et al. 1997. Nicotinamide adenine dinucleotide synthetase activity in erythrocytes as a tool for the biological monitoring of lead exposure. Int Arch Occup Environ Health 70(3) 195-198. 

Early investigators assumed that human erythrocytes could convert nicotinic acid, but not the amide, into NAD (H3, H8). There are later reports to the contrary, i.e., that nicotinamide, but not the acid, produced increased synthesis of NAD-active material (L3). To resolve these discrepancies, standards for assaying nicotinic acid activity were prepared by mixing equal weights of the acid and amide, because these... 

H3. Handler, P., and Kohn, H. I., The mechanism of cozymase synthesis in the human erythrocyte a comparison of the role of nicotinic acid and nicotinamide. J. Biol. Chem. 150, 447-452 (1943). 

L3. Leder, H. G., and Handler, P., Synthesis of nicotinamide mononucleotide by human erythrocytes in vitro. J. Biol. Chem. 189, 889-899 (1951). 

Pure NADP+ was isolated from red blood cells in 1934 by Otto Warburg and W. Christian, who had been studying the oxidation of glucose 6-phosphate by erythrocytes.13 They demonstrated a requirement for a dialyzable coenzyme which they characterized and named triphosphopyridine nucleotide (TPN+, but now officially NADP+ Fig. 15-1). Thus, even before its recognition as an important vitamin in human nutrition, nicotinamide was identified as a component of NADP+. 

It is an important source of reduced nicotinamide-adenine dinucleotide phosphate (NADPH) which maintains erythrocyte glultathione in its reduced form. 

Figure 21 -8 Major glycolytic pathways of the erythrocyte. Substrates are in uppercase type, and enzymes are in parentheses. EMP, The Embden-Meyerhof pathway HMP hexose monophosphate pathway or pentose shunt RLC, the Rapoport-Luebering cycle ADP, adenosine diphosphate ATP, adenosine triphosphate NAD, nicotinamide-adenine dinudeotide NADH, reduced nicotinamide-adenine dinucleotide NADP, nicotinamide-adenine dinucleotide phosphate NADPH, reduced nicotinamide-adenine dinucleotide phosphate.The step from ribulose-5-phosphate, which is shown as being catalyzed by transketolase and transaldolase, is an abbreviation of this portion of the HMR...

Dietary NAD and NADP are hydrolyzed by enzymes, such as NAD glycohydrolase, in the intestinal mucosa to release nicotinamide, which together with any nicotinic acid is rapidly absorbed in both the stomach and intestine by an Na -dependent facilitated diffusion at low concentrations and passive diffusion at higher concentrations. Nicotinamide is the main circulating form in the plasma, either postabsorption or by release from hydrolyzed liver NAD, and this can be taken up by most tissue requiring NAD by simple diffusion, though there is evidence of a facilitated transport in the erythrocyte. ... 

Lan SJ, Henderson LM. Uptake of nicotinic acid and nicotinamide by rat erythrocytes. J Biol Chem 1968 243 3388-94. 

Injected tryptophan causes a rise in erythrocyte DPN in the rat (562). The problem was taken up by Elvehjem and his school (c/. review, 224), who at first found tryptophan to be more active than nicotinamide in stimulating synthesis of rat-liver DPN and TPN (924, 925). Nicotinamide had, however, a sparing effect in young, but not in adult, rats (925). In pyridoxine deficiency conversion of tryptophan to pyridine nucleotides... 

Zerez, C. R., Roth, E. F., Jr., Schulman, S., and Tanaka, K. R. (1990). Increased nicotinamide adenine dinudeotide content and synthesis in Plasmodium falciparum-infected human erythrocytes. Blood 75,1705-1710. 

The status of niacin in relation to most other vitamins is different as it can be synthesized by humans to some extend from tryptophan. Body status determination has been based on the determination of urinary excretion of niacin metabolites, predominately N-methyl-2-pyridone-5-carboxylamide and N-methyl-nicotinamide. The ratio of these compounds has been used as indicator of niacin status. Recent studies suggest that the determination of the two niacin-derived coenzymes, NAD and NADP, in erythrocytes, and their ratio are more reliable indicators of niacin status. However, a broadly accepted and easy to use determination method does not seem to exist. 

Micheli and Sestini [439] report on the study of NAD/NAPD precursors, metabolites, and catabolites (e.g., nicotinate and its mononucleotide, nicotinamide and its mononucleotide, AMP, inosine monophosphate) in oythrocytes. Samples were extracted fixim red blood cells and analyzed on a C g column (A — 260 nm and 280 nm). A 93/7 (hold 5 min) — 70/30 (at 6 min hoM 4 min) water (0.1 M KH2PO4 buffer at pH 5.5 with 8mM tetrabutylarmnonium sulfate)/(70/30 water [0.1 M KH2PO4 buffer at pH 5.5 with 8mM tetrabutylarmnonium sulfate]/methanol) gradient generated excellent peak shapes and resolution. Reported erythrocyte levels ranged fix>m 10 to 50 nmol/mL. 

The erythrocyte transketolase (ETK) activation assay (also known as the saturation test) measures the functional capacity of the enzyme transketolase in red blood cells i.e. erythrocytes). Transketolase is a thiamine-dependent enzyme in the non-oxidative branch of the pentose phosphate pathway (PPP), a process of glucose turnover that produces nicotinamide adenine dinucleotide phosphates (NADPH) as reducing equivalents and pentose sugars as essential components of nucleotides. In the absence of adequate thiamine, the PPP output is compromised. 

Pyridine Nucleotides. Nucleoside phosphorylase is capable of using the base nicotinamide. The product of the reaction of this base with ribose-l-phosphate is nicotinamide riboside. The formation of the corresponding nicotinamide mononucleotide is catalyzed by a typical kinase, using ATP. A specific enzyme purified from human erythrocytes has been shown to form nicotinamide mononucleotide by a second mechanism in which PRPP and nicotinamide react to form inorganic pyrophosphate and... 

M Rocchingiani, V Michaeli, JA Duley, HA Simmonds. Determination of nicotinamide phosphoribosyltransferase activity in human erythrocytes high-performance liquid chromatography-linked method. Anal Biochem 205 334-336, 1992. 

This enzyme is quite weak and actually may not play a role in DPN synthesis. A reaction (2d) between nicotinamide and 5-phosphoribose-l-pyrophosphate (PRPP) has been detected by Preiss and Handler 118) in human erythrocytes. 

A considerable advance in elaborating the pathway of pyridine coenzyme synthesis resulted from the contributions of Preiss and Handler (118, 1B6-1B8). Before discussing the experiments of these investigators, it may be of value to review some of the earlier work on the metabolism of nicotinic acid and nicotinamide in erythrocytes. It has been known for some time that nicotinic acid taken orally results in a significant increase in the pyridine nucleotide content of human red blood cells (1B9, ISO). When equal concentrations of nicotinamide were given under identical conditions, there was no effect on the erythrocyte DPN level. Isolated erythrocytes have also been found to show a rise in DPN when incubated with nicotinic acid and not with nicotinamide. However, incubation with nicotinamide leads to a marked accumulation of nicotinamide mononucleotide (ISl). In this connection, it is of importance to point out that the level of the DPN pyrophosphorylase is extremely low in the red blood cell (ISB). 

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