【摘要】 以6-磷酸葡萄糖、磷酸苯二钠、β-萘酚磷酸和对硝基苯磷酸为底物,研究了L-苯丙氨酸对人胎盘碱性磷酸酶的抑制作用。结果发现,L-苯丙氨酸在不同条件下可以呈现抑制作用,也可呈现激活作用。不同类型的底物对L-苯丙氨酸的这两种相反的作用均给予显著的影响。在前三种底物条件下,当高底物浓度时,L-苯丙氨酸表现出反竞争性抑制作用;低底物浓度时,则呈现激活作用。这种激活作用随底物浓度的升高而减弱。在后一种底物条件下,低浓度的L-苯丙氨酸表现出非竞争性抑制作用;高浓度时,则表现出激活作用。底物浓度对L-苯丙氨酸的这种动力学行为无影响。本文试图对碱性磷酸酶的这种复杂动力学行为予以理论上的探讨。更多还原

【Abstract】 Inhibition of L-phenylalanine(L-Phe)on human placental alkaline phosphatase was studied with glucose-6-phosphate, phenyl disodium phosphate,β-naphthol phosphate and p-nitrophenol phosphate as the substrates respectively. The results were that L-Phe acted either as an inhibitor or activator according to the reactive conditions, and different substrates showed remarkable influences on the alternative effects.As the former three substrates were employed,at high substrate concentration, L-Phe inhibited the enzyme uncompetitively and activated the enzyme at low substrate concentration.This activation was getting weaker with the increase of substrate concentration. As the last substrate was employed, low concentration of L-Phe expressed noncompetitive inhibition, but at high concentration, the effect became activated. Substrate concentration showed no influence on the kinetic behavior of L-Phe. In our present paper, those complicated kinetics were tentatively explained in theory.更多还原