Effects of a dietary excess of leucine on the metabolism of tryptophan in the rat: a mechanism for the pellagragenic action of leucine

摘要: In order to investigate the mechanism of pellagragenic action excess dietary leucine, rats were fed on diets providing a minimally-adequate amount tryptophan, with no preformed niacin, and without addition 15 g leucine/kg diet. This leucine in diet has been demonstrated previously lead depletion blood liver nicotinamide nucleotides. The metabolism tryptophan was assessed by measurement production 14CO2 after administration [methylene-14C]tryptophan estimate activity kynureninase (L-kynurenine hydrolase, EC 3.7.1.3) [benzene ring U-14C]tryptophan picolinate carboxylase (aminocarboxymuconate semialdehyde decarboxylase, 4.1.1.45). A led inhibition increased carboxylase. Both these effects would result reduction rate acroleylaminofumarate semialdehyde) quinolinic acid hence These two provide an explanation for effect animals that are wholly or partly reliant endogenous synthesis from meet their requirements nucleotides, presumably also explain man.