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研究了乙胺硫脲对蘑菇酪氨酸酶单酚酶和二酚酶活性的抑制效应。结果表明,乙胺硫脲对酪氨酸酶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%的乙胺硫脲浓度(IC50)分别为14.8和45.2μmol/L。在降低酪氨酸酶酶活的同时,乙胺硫脲能明显延长单酚酶和二酚酶的延滞时间。探讨了二酚酶延滞时间产生的原因:乙胺硫脲与酪氨酸酶催化氧化产物多巴醌反应,形成了无色的L-DOPA衍生物,从而阻断了多巴色素的形成。乙胺硫脲对二酚酶的抑制作用表现为不可逆的竞争性抑制。并且,在反应体系中存在的铜离子仅能够部分的阻止乙胺硫脲对酪氨酸酶的抑制。
The inhibitory effect of ethidium thiourea on the activity of tyrosinase monophenol and diphenolase was studied. The results showed that ethidium thiourea had an inhibitory effect on tyrosinase monophenolase and diphenolase, resulting in IC50 values of IC50 for monophenolase activity and diphenolase activity of 50%, respectively, of 14.8 And 45.2 μmol / L. While reducing tyrosinase activity, ethidium thiourea can significantly prolong the delay time of monophenol and diphenolase. The reasons for the delayed production of diphenolase were discussed: Ethidium thiourea and tyrosinase catalyzed the oxidation of the product, dopaquinone, resulting in the formation of a colorless L-DOPA derivative, which blocked the formation of dopachrome. Ethidium thiourea inhibition of diphenol showed irreversible competitive inhibition. In addition, copper ions present in the reaction system can only partially inhibit the inhibition of tyrosinase by ethanthiride.