The synthesis of nicotinuric acid by rat-kidney preparations

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Abstract
Slices and homogenates of rat kidney and liver have been shown to synthesize nicotinuric acid from nicotinic acid and glycine. Nicotinuric acid was identified chromatographically, by its spectrum and by hydrolysis to nicotinic acid and glycine. The synthesis in homogenates was stimulated by fumarate and adenosine triphosphate. The synthetic activity of rat-kidney homogenate was located entirely in the nuclear and mito- chondrial fractions. None was found in the microsome and soluble fractions even when an energy- supplying system was added. About half the activity of the nuclear fraction appeared to be due to the nuclei, the remainder being caused by contaminating mitochondria. Nicotinuric acid synthesis by rat-kidney mitochondria was completely dependent upon added nicotinic acid, glycine, fumarate and adenosine triphosphate. The synthesis was inhibited by 2,4-dinitrophenol, benzoic acid and potassium fluoride. The properties of the synthetic system in mitochondria are described. Nicotinamide was not synthesized by the enzyme system which synthesized nicotinuric acid.