Egashira Y, Komine T, Ohta T, Shibata K, Sanada H
Department of Bioproduction Science, Faculty of Horticulture, Chiba University, Matsudo, Japan.
J Nutr Sci Vitaminol (Tokyo). 1997 Apr;43(2):233-9. doi: 10.3177/jnsv.43.233.
The change of tryptophan-niacin metabolism in D-galactosamine (D-galN) injected rats was investigated. Rats fed with niacin-free diets containing 40% casein for 11 days were injected with D-galN (0.8 g/kg body weight). The urinary excretions of nicotinamide and its metabolites, and the activity of liver alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) (EC 4.1.1.45), a key enzyme of tryptophan-niacin metabolism, were assayed. As the result, the urinary excretions of N1-methylnicotinamide (MNA), N1-methyl-2-pyridone-5-carboxamide (2-Py), N1-methyl-4-pyridone-3-carboxamide (4-Py) and their sum (nicotinamide+MNA+2-Py+4-Py) were higher in the D-galN-injected group than in the control group. Hepatic ACMSD activity in the D-galN-injected group was lower than that of the control group. These results suggest that the increase in urinary excretion of nicotinamide and its metabolites after the injection of D-galN is considered to be attributable to a decrease in liver ACMSD activity.
研究了注射D-半乳糖胺（D-galN）的大鼠色氨酸-烟酸代谢的变化。给喂食含40%酪蛋白的无烟酸饮食11天的大鼠注射D-半乳糖胺（0.8 g/kg体重）。检测了烟酰胺及其代谢产物的尿排泄量，以及色氨酸-烟酸代谢的关键酶肝脏α-氨基-β-羧基粘康酸-ε-半醛脱羧酶（ACMSD）（EC 4.1.1.45）的活性。结果显示，注射D-半乳糖胺组的N1-甲基烟酰胺（MNA）、N1-甲基-2-吡啶酮-5-甲酰胺（2-Py）、N1-甲基-4-吡啶酮-3-甲酰胺（4-Py）及其总和（烟酰胺+MNA+2-Py+4-Py）的尿排泄量高于对照组。注射D-半乳糖胺组的肝脏ACMSD活性低于对照组。这些结果表明，注射D-半乳糖胺后烟酰胺及其代谢产物尿排泄量的增加被认为归因于肝脏ACMSD活性的降低。
