漆酶催化儿茶素及儿茶酚合成黑色素的研究

Synthesis of Melanin with Catechin and Catechol by Laccase

漆酶是一种含铜的多酚氧化酶,具有广泛的底物催化性。在漆酶的介导下对不同酚类底物合成带色产物进行了研究,发现儿茶素和儿茶酚能够合成黑色素。重点研究了黑色素合成的影响因素:底物的比例对黑色素的影响很大,1∶1为最佳比例;光照对黑色素的合成几乎无影响;漆酶活力越高对反应越有利;不同来源的漆酶催化反应的最适温度和最适p H不同;有机溶剂乙醇、正丙醇、正丁醇和丙酮对黑色素合成有促进作用,而有机溶剂甲醇和异戊醇又起抑制作用;金属离子Na+、Mn2+、Mg2+、Sr2+、K+有一定的抑制作用,并且浓度越高抑制作用越强,而加入Cu2+、Fe2+、Fe3+时分别产生青灰色、绿色、灰黑色沉淀,没有黑色素生成;底物浓度对黑色素合成的影响呈钟形,0.1 mol/L最适宜;震荡有利于漆酶催化黑色素的合成。通过漆酶合成的黑色素有望用于改进染发剂的配方。

Laccase is a copper-containing polyphenol oxidase with wide range of substrate specificity. Colored products were generated via lacease-mediated synthesis of different phenolic substrates in the present study, where melanin was found to be produced using cate- chin and catechol as substrates. This study thus focused on the influencing factors involved in the synthesis reactions of catechin and catechol. The results showed that the ratio of the substrate greatly affected dye synthesis with the optimum ratio of 1 ： 1 ; light or dark ex- erted no apparent effect on dye synthesis; the higher laccase activity promoted higher dye synthesis; different optimal temperature and pH were found for different laccases to catalyze the reaction ; dye synthesis was stimulated by some organic solvents, i. e., ethanol, pro- panol, butanol and acetone, while inhibited by such organic solvents such as methanol and isoamyl alcohol; metal ions such as Na^＋,Mn^2＋,Mg^2＋,Sr^2＋,K^＋ inhibited dye synthesis to some extent, while Cu^2＋,Fe^2＋,Fe^3＋ resulted in gray, green, gray-black precipitation, respectively, without dye synthesized; substrate concentration also influnced on dye synthesis with favoriate concentration of 0. 1 mol/L; shaking condition was favorable to dye synthesis. Laccase-mediated melanin synthesis might serve as a novel alternative for.hair dye formula.