漆树漆酶的催化氧化作用——Ⅴ.漆酶/O_2体系获取半醌自由基的研究  

CATALYZED OXIDATION BY RHUS VERNICIFERA LACCASE Ⅴ.The generation of semiquinone radical using laccase/O_2 system

作　　者：王光辉[1] 江涛[1] 张昌军 李江泉 

机构地区：[1]武汉大学化学系

出　　处：《武汉大学学报（自然科学版）》1992年第4期88-94,共7页Journal of Wuhan University(Natural Science Edition)

基　　金：国家自然科学基金

摘　　要：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。An method for the effective generation of high steady state concentration of semiquinone radicals was established from catalyzed oxidation of 2,3-dicyanohydroquinone(DDHQH_2)and its dihalid derivatives(DDCQH_2,DDBQH_2 and DDIQH_2)by laccase/O_2 system in static condition.These sub- strates contain strong electron with drawing groups,which can cause delocalization of the free elec- tron.ESR hyperfine splitting structure was exhibited that they are semiquinone anion-radicals.When the concentration of DDCQH_2,DDBQH_2 and DDIQH_2 was 7.74×10^(-5)mol—L^(-1),9.15×10^(-5)mol· L^(-1)and 6.95×10^(-5)mol·L^(-1),the steady state concentration of semiquinone anion-radicals could be achieved to 2.54×10^(-5)mol·L^(-1),2.67×10^(-5)mol·L^(-1)and 2.12×10^(-5)mool·L^(-1),respectively. These semiquinone anion-radicals that generated from DDCQH_2,DDCBQH_2 and DDIQH_2,could be ex- tracted by EtOAc according to an ion pair form,and have identical wave spectrum character with the chemical synthetic semiquinone radical sodium.These results showed that,the laccase/O_2 system can serve as a good enzyme model.Moreover,it was found by the authors that the laccase-catalyzed oxida- tion of substrates possessed a specificity of consecutive reaction obviously.

关 键 词：漆树 半醌 酶 催化 游离基 阴离子 

分 类 号：Q946.5[生物学—植物学]