Kaneko M, Fujimoto S, Kikugawa M, Kontani Y, Tamaki N
Laboratory of Nutritional Chemistry, Faculty of Nutrition, Kobe-Gakuin University, Japan.
J Nutr Sci Vitaminol (Tokyo). 1991 Oct;37(5):517-28. doi: 10.3177/jnsv.37.517.
The effect of dietary protein on pyrimidine-metabolizing enzymes was studied in the rat. The activities of dihydropyrimidine dehydrogenase and beta-ureidopropionase in the livers of rats fed a protein-free diet were significantly decreased, while the activity of dihydropyrimidinase was unaffected. Protein deficiency (5%) also decreased the activity of beta-ureidopropionase. On the other hand, a high-protein diet (60%) increased the level of beta-ureidopropionase. The activities of beta-alanine-oxoglutarate aminotransferase (aminobutyrate aminotransferase) and D-3-aminoisobutyrate-pyruvate aminotransferase ((R)-3-amino-2-methylpropionate-pyruvate aminotransferase), which are present in mitochondria, depended on the amount of protein in the diet. Ammonium ions supplemented in the diet and given by injection did not affect the activities of rat liver pyrimidine-metabolizing enzymes (dihydropyrimidine dehydrogenase, dihydropyrimidinase, beta-ureidopropionase, beta-alanine-oxoglutarate aminotransferase and D-3-aminoisobutyrate-pyruvate aminotransferase). Dietary uridine resulted in the accumulation of uracil in the liver, but did not affect the activities of pyrimidine-metabolizing enzymes.
在大鼠中研究了膳食蛋白质对嘧啶代谢酶的影响。喂食无蛋白饮食的大鼠肝脏中，二氢嘧啶脱氢酶和β-脲基丙酸酶的活性显著降低，而二氢嘧啶酶的活性未受影响。蛋白质缺乏（5%）也会降低β-脲基丙酸酶的活性。另一方面，高蛋白饮食（60%）会提高β-脲基丙酸酶的水平。存在于线粒体中的β-丙氨酸-α-酮戊二酸氨基转移酶（氨基丁酸氨基转移酶）和D-3-氨基异丁酸-丙酮酸氨基转移酶（(R)-3-氨基-2-甲基丙酸-丙酮酸氨基转移酶）的活性取决于饮食中的蛋白质量。饮食中补充并注射的铵离子不会影响大鼠肝脏嘧啶代谢酶（二氢嘧啶脱氢酶、二氢嘧啶酶、β-脲基丙酸酶、β-丙氨酸-α-酮戊二酸氨基转移酶和D-3-氨基异丁酸-丙酮酸氨基转移酶）的活性。膳食尿苷会导致肝脏中尿嘧啶的积累，但不会影响嘧啶代谢酶的活性。
