4-氨基苯甲酸对蘑菇酪氨酸酶的抑制作用机理研究

Inhibitory Effects of 4-Aminobenzoic Acid on Mushroom Tyrosinase

报道了4-氨基苯甲酸(4-aminobenzoic acid)对蘑菇酪氨酸酶单酚酶和二酚酶活力的影响和抑制效应.结果表明,4-氨基苯甲酸对蘑菇酪氨酸酶的单酚酶和二酚酶活性均有抑制作用.导致单酚酶活力和二酚酶活力下降50%的抑制剂浓度(IC50)分别为0.35和0.30 mmol/L.4-氨基苯甲酸对单酚酶的迟滞时间有明显的延长效应,1.0 mmol/L可使单酚酶的迟滞时间从30.5 s延长到155.1 s,增加了4.4倍.4-氨基苯甲酸对二酚酶的抑制作用表现为混合型可逆抑制作用,抑制常数(KI和KIS)分别为0.259和1.46 mmol/L.

Tyrosinase （EC 1.14.18. 1） catalyzes both the hydroxylation of tyrosinase into odiphenols and the oxidation of o-diphenols into o-quinones that form brown or black pigments. In the present paper,the effects of 4-aminobenzoie acid on the activity of mushroom tyrosniase were studied. The results showed that 4-aminobenzoic acid could inhibit both monophenolase activity and diphenolase activity of the enzyme. For the monophenolase activity, 4-aminobenzoic acid lengthened the lag time and decreased the steadystate activity. With increasing inhibitor concentration,the lag time changed from 30.5 seconds in its absence to 155.1 seconds in the presence of 1.0 mmol/L and the IC50 value was estimated to be 0. 35 mmol/L. For the diphenolase activity, the kinetic analysis showed that the inhibition of 4-aminobenzoic acid on the diphenolase activity of the enzyme was reversible and belonged to mix-type,and the inhibition constants （K1 and KLS） were determined to be 0. 259 and 1.46 mmol/L,respectively. The IC5o value was estimated to be 0.30 mmol/L. This research may offer some references for designing and synthesizing some novel and effective tyrosinase inhibitors. Further more,it may improve the use of 4-aminobenzoic acid on the field of depigmentation.