Utilization of tryptophan, nicotinamide and nicotinic acid as precursors for nicotinamide nucleotide synthesis in isolated rat liver cells.

摘要: 1. Incubation of isolated rat hepatocytes with nicotinamide or nicotinic acid showed that while both vitamers were taken up from the incubation medium, neither was utilized to any significant extent as a precursor nucleotide coenzymes, NAD and NADP, capable preventing loss nucleotides occurs on incubating cells. 2. tryptophan de novo synthesis permitted replacement lost during incubation; at high concentrations there an increase above initial intracellular concentration NAD(P). also resulted in formation release cells considerable amount niacin, well two principal metabolities NAD(P), N1-methyl methyl pyridone carboxamide. 3. It is suggested that, liver, performed niacin not for synthesis, indeed function liver appears be tryptophan, its use by extrahepatic tissues lack pathway tryptophan.