Tsao C S, Young M
Linus Pauling Institute of Science and Medicine, Palo Alto, California 94306.
Life Sci. 1989;45(17):1553-7. doi: 10.1016/0024-3205(89)90421-9.
The effect of exogenous ascorbic acid intake on biosynthesis of ascorbic acid in mice has been studied. After the mice were on diets containing added ascorbic acid for two months, the activities of ascorbic acid synthesizing enzymes in the mouse liver homogenates were measured using L-gulono-gamma-lactone as a substrate. Exogenous ascorbic acid intake (0.5, 1 or 5% in the diet) was able to increase the concentration of ascorbic acid in the blood and to decrease the activities of ascorbic acid synthesizing enzymes in mouse liver. The results suggest that ascorbic acid synthesis was controlled by local regulatory mechanism or by the concentration of ascorbic acid in the hepatic portal blood. Ingestion of dietary erythorbic acid, a stereoisomer of ascorbic acid, had no effect on the activities of ascorbic acid synthesizing enzymes.
已研究了外源摄入抗坏血酸对小鼠体内抗坏血酸生物合成的影响。小鼠在含添加抗坏血酸的日粮中饲养两个月后，以L-古洛糖酸-γ-内酯为底物，测定小鼠肝脏匀浆中抗坏血酸合成酶的活性。外源摄入抗坏血酸（日粮中含量为0.5%、1%或5%）能够提高血液中抗坏血酸的浓度，并降低小鼠肝脏中抗坏血酸合成酶的活性。结果表明，抗坏血酸的合成受局部调节机制或肝门静脉血中抗坏血酸浓度的控制。摄入抗坏血酸的立体异构体——异抗坏血酸，对抗坏血酸合成酶的活性没有影响。
