The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration lea...The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration leading to 50% relative activity lost （IC50） was estimated to be 0.15 mmol·L^-1. The inhibition mechanism obtained from Lineweaver-Burk plots shows that ferulic acid is a competitive inhibitor and the inhibition of tyrosinase by ferulic acid is a reversible reaction. The equilibrium constant for ferulic acid binding with the tyrosinase was determined to be 0.25 mmol·L^-1 for diphenolase. Keywords tyrosinase, ferulic acid, kinetics, inhibition, L-DOPA, diphenolase展开更多
目的:采用酶促反应动力学方法研究补骨脂酚对酪氨酸单酚酶和二酚酶活性的影响,并考察补骨脂酚对酪氨酸酶的作用机制及动力学参数。方法:在p H 6.8的磷酸盐缓冲体系中,分别以L-酪氨酸和左旋多巴为底物,37℃反应后在475 nm处测定吸光度,...目的:采用酶促反应动力学方法研究补骨脂酚对酪氨酸单酚酶和二酚酶活性的影响,并考察补骨脂酚对酪氨酸酶的作用机制及动力学参数。方法:在p H 6.8的磷酸盐缓冲体系中,分别以L-酪氨酸和左旋多巴为底物,37℃反应后在475 nm处测定吸光度,研究补骨脂酚对酪氨酸酶催化反应进程和酶活性抑制的影响,计算抑制动力学参数。结果:补骨脂酚对酪氨酸单酚酶和二酚酶均有抑制作用,半抑制浓度分别为1.49,0.41 mmol·L^(-1),其中对酪氨酸二酚酶的抑制作用表现为可逆抑制,其抑制作用表现为竞争性抑制,抑制常数0.955 mmol·L^(-1)。结论:在低浓度范围内,补骨脂酚对酪氨酸酶的抑制作用较熊果苷更明显,具有开发成天然酪氨酸酶抑制剂的潜力。展开更多
基金Supported by the Natural Science Foundation of Guangdong Province (No. 011563, No. 04020114).
文摘The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration leading to 50% relative activity lost （IC50） was estimated to be 0.15 mmol·L^-1. The inhibition mechanism obtained from Lineweaver-Burk plots shows that ferulic acid is a competitive inhibitor and the inhibition of tyrosinase by ferulic acid is a reversible reaction. The equilibrium constant for ferulic acid binding with the tyrosinase was determined to be 0.25 mmol·L^-1 for diphenolase. Keywords tyrosinase, ferulic acid, kinetics, inhibition, L-DOPA, diphenolase
