利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的...利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的有效途径。含二卤的2,3-二氰基氢醌底物产生的半醌自由基阴离子能以离子对形式被乙酸乙酯萃取。研究表明,在半醌自由基的酶法研究中,漆酶/O_2体系有可能成为一个更有效的酶模型。实验证明,漆酶对底物的催化氧化过程具有鲜明的连串反应特征。展开更多
The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the ...The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).展开更多
基金supported by grants from the National Natural Science Foundation of China(No.81770855)the Taishan Scholars Foundation of Shandong Province(No.ts201511057)Academic Promotion Program of Shandong First Medical University&Shandong Academy of Medical Sciences,China(No.2019QL010,2019PT009)。
文摘利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的有效途径。含二卤的2,3-二氰基氢醌底物产生的半醌自由基阴离子能以离子对形式被乙酸乙酯萃取。研究表明,在半醌自由基的酶法研究中,漆酶/O_2体系有可能成为一个更有效的酶模型。实验证明,漆酶对底物的催化氧化过程具有鲜明的连串反应特征。
文摘The enzymatic oxidation of (+)-catechin (Cat) with copper-containing oxidase, tyrosinase, was applied to hair colouring in the study. The Cat is oxidised to be o-benzoquinone form, the catechinone, which works as the hair dyestuff. Four kinds of hair colouring techniques using Cat were examined and each of their dyeability was compared in order to improve it. The first dyeing method is dyeing hair by the redissolved catechinone, which is preliminarily obtained by the oxidation of Cat (Redissolution Dyeing Method). The second one is dyeing hair in the dye solution just after the dye being formed by the enzymatic reaction (Sequential Dyeing Method). The third one is dyeing hair in solution containing Cat and the dyeing process is accompanied by the oxidation of Cat (Simultaneous Oxidation Dyeing Method). The fourth one is two-step dyeing that the hair immersed in Cat solution at the first step and then it is oxidised enzymatically to colour at the second step (Post-Oxidation Dyeing Method). The hair is dyed pale yellow by Redissolution Method, deeper yellowish brown by Sequential and Simultaneous Oxidation Dyeing Method and slightly reddish brown by Post-Oxidation Method with Cat. The order of their dyeability is the Simultaneous Oxidation ≈ Post-Oxidation > Sequential > Redissolution Dyeing Method at 30°C. The dyeability of Redissolution Method increases with an increase in dyeing temperature (T) between 20°C - 60°C. In Simultaneous Oxidation Method, the T increment also provides higher dyeability, and the colour of dyed hair becomes duller over 50°C. The Post-Oxidation Method shows higher dyeability at the lower oxidation temperature (20 °C - 40°C).
