A comparative study of the synthesis of nicotinamide nucleotides by erythrocytes of some vertebrates

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Abstract
Seven mammalian, 1 avian and 1 amphibian species were studied for the capacity of their erythrocytes to synthesize nicotinamide nucleotides in vitro. Under the conditions used, only human erythrocytes and nucleated erythrocytes of pigeon and frog were capable of synthesizing nicotinamide nucleotides from both nicotinamide and nicotinic acid. On the other hand, rat blood was unable to form nicotinamide nucleotides from either of these substrates. Human, guinea-pig, pigeon and frog erythrocytes synthesized nicotinamide nucleotides from nicotinamide and glucose. Monkey erythrocytes synthesized nicotinamide nucleotides from nicotinamide only in the presence of glutamine, suggesting that in this species the conversion of nicotinamide into nicotinic acid was an essential step in the formation of nicotinamide nucleotides. Human, monkey, pigeon and frog erythrocytes could synthesize appreciable amounts of nicotinamide nucleotides from nicotinic acid, glucose and glutamine, whereas this did not occur in guinea-pig erythrocytes. Nicotinic acid was an effective precursor of nicotinamide nucleotides only at low concentrations.