Pawelek J M
Department of Dermatology, Yale University School of Medicine, New Haven, CT 06510.
Biochem Biophys Res Commun. 1990 Feb 14;166(3):1328-33. doi: 10.1016/0006-291x(90)91011-g.
Dopachrome conversion factor is an enzymatic activity associated with the pigmentary system which catalyzes the conversion of dopachrome, an intermediate in melanin biosynthesis, to dihydroxyindole-2-carboxylic acid (DHICA). To date, the mechanism of action of DCF has been unknown because all previous assays have employed a dopachrome substrate contaminated with L-dopa. It has therefore not been possible to determine whether L-dopa acts as a hydrogen donor in the reaction or whether the formation of DHICA occurs through an isomerization of dopachrome. In this study it is shown that DCF catalyzes the conversion of dopachrome to DHICA equally well in the presence or absence of L-dopa. The DCF-mediated reaction thus appears to be an isomeric rearrangement of hydrogen ions from one portion of the dopachrome molecule to another. The results indicate that the name "dopachrome isomerase" appropriately describes the function of DCF.
多巴色素转换因子是一种与色素系统相关的酶活性物质，它催化黑色素生物合成过程中的中间产物多巴色素转化为二羟基吲哚 -2- 羧酸（DHICA）。迄今为止，由于之前所有的测定都使用了被左旋多巴污染的多巴色素底物，所以DCF的作用机制一直未知。因此，无法确定左旋多巴在反应中是否作为氢供体，或者DHICA的形成是否通过多巴色素的异构化发生。在本研究中表明，无论有无左旋多巴，DCF都能同样良好地催化多巴色素转化为DHICA。因此，DCF介导的反应似乎是氢离子从多巴色素分子的一部分到另一部分的异构重排。结果表明，“多巴色素异构酶”这个名称恰当地描述了DCF的功能。
