Age Difference in Nicotinamide Mononucleotide Synthesis by Human Erythrocytes

Abstract

IT is well known that human erythrocytes contain an active enzyme system capable of synthesizing considerable amounts of nicotinamide mononucleotide from nicotinamide added in vitro ¹. The nicotinamide mononucleotide synthetase is very specific for human erythrocytes as the only other mammal in the blood cells of which it could be detected is the guinea pig². It was found here, however, that the activity of the given synthetase in human erythrocytes can be shown at the beginning of the fifth month of life when its activity rapidly reaches almost a maximum level, remaining then practically without change. Whereas mammalian erythrocytes not synthesizing nicotinamide mononucleotide are characterized by a high content of pyridine nucleotides, their amount being several times higher than in human and guinea pig erythrocytes², the non-synthesizing child erythrocytes contain even somewhat less pyridine nucleotides than those of adult humans.