Nicotinic Acid Biosynthesis: Control by an Enzyme that Competes with a Spontaneous Reaction

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Science  21 Aug 1964:
Vol. 145, Issue 3634, pp. 817-819
DOI: 10.1126/science.145.3634.817


Extracts of livers from diabetic rats contain normal amounts of the enzymes needed to convert 3-hydroxyanthranilic acid to nicotinic acid nucleotide. The decreased capacity of diabetic animals to synthesize nicotinic acid is therefore attributed to increased amounts of picolinic carboxylase, which competes for a common intermediate with the spontaneous reaction in which quinolinic acid is formed as a precursor of nicotinic acid. These studies were facilitated by the synthesis of 3-hydroxyanthranilic acid labeled with carbon-14 in positions 3 and 6