Chan J, Lee K H
J Pharm Sci. 1975 Jul;64(7):1182-5. doi: 10.1002/jps.2600640711.
Mechanisms of inhibitory action of sodium salicylate on L-glutamine-D-fructose-6-phosphate aminotransferase, prepared from rat gastric mucosa, were studied. Sodium salicylate at lower concentrations (10-20 mM) inhibited reversibly aminotransferase activity by competing with fructose-6-phosphate. At higher concentrations, sodium salicylate inactivated the enzyme irreversibly, with an inactivation rate following first-order kinetics with respect to the enzyme concentration. Uridine-5'-diphospho-N-acetylglucosamine is an endogenous feedback inhibitor. It inhibited the aminotransferase-catalyzed reaction also by competing with fructose-6-phosphate but with an inhibiting activity 1000 times that of sodium salicylate. Uridine-5'-diphospho-N-acetylglucosamine reduced the salicylate inhibition of the enzymic reaction and protected the enzyme from salicylate-induced irreversible inactivation. At a fixed concentration of uridine-5'-diphospho-N-acetylglucosamine (7x10(-6)M), an increase of salicylate concentration produced an increase in enzyme activity as compared with the control.
研究了水杨酸钠对从大鼠胃黏膜制备的L-谷氨酰胺-D-果糖-6-磷酸氨基转移酶的抑制作用机制。较低浓度（10 - 20 mM）的水杨酸钠通过与6-磷酸果糖竞争，可逆地抑制氨基转移酶活性。在较高浓度下，水杨酸钠使酶不可逆失活，失活速率相对于酶浓度遵循一级动力学。尿苷-5'-二磷酸-N-乙酰葡糖胺是一种内源性反馈抑制剂。它也通过与6-磷酸果糖竞争来抑制氨基转移酶催化的反应，但其抑制活性是水杨酸钠的1000倍。尿苷-5'-二磷酸-N-乙酰葡糖胺降低了水杨酸盐对酶反应的抑制作用，并保护酶免受水杨酸盐诱导的不可逆失活。在固定浓度的尿苷-5'-二磷酸-N-乙酰葡糖胺（7×10(-6)M）下，与对照相比，水杨酸盐浓度的增加导致酶活性增加。
