邻苯三酚自氧化法适于测定SOD活性吗?

Can be used to assay SOD activity by means of pyrogallol oxidation?

用邻苯三酚自氧化法测定了Cu-ZnSOD(Superoxidedismutase,SOD)及根据天然超氧化物歧化酶活性部位结构设计、合成的一些模型化合物(themodelsofSOD,MSOD)活性.测试结果表明:Cu-ZnSOD和含Cu( )、Fe( )、Mn( 、 )的SOD模型化合物随浓度升高,有的对邻苯三酚氧化表现为负抑制(即促进邻苯三酚氧化);另一部分化合物在较低浓度表现为抑制,较高浓度表现为负抑制的交替变化;或抑制率的无规则变化.本文对出现负抑制的内在根源进行了探讨,鉴于邻苯三酚自氧化的复杂反应机理;含Cu( )、Fe( )、Mn( 、 )SOD模型化合物的多酚氧化酶活性和Fenton反应催化活性,及MSOD中金属离子的Lewis酸性,不宜采用邻苯三酚自氧化法测定SOD活性.

CuZn superoxide dismutase (SOD) and some of model compounds (models of SOD, MSOD) containing copper(Ⅱ), iron (Ⅲ) and manganese (Ⅱ?Ⅲ), which are designed and synthesized base on the active sites of natural SODs, have been performed by means of pyrogallol autoxidation in the air and a weakly alkaline buffer solution (pH=8.2) with Ntris (hydroxymethyl) amino methaneHCl. The measured results show that most of the model compounds exhibit negative inhibition to the oxidative rate of pyrogallol, in other words, they promote pyrogallol oxidation. The others show inhibition in the lower concentration range, but nagative inhibition in the higher concentration range or disorder change. These phenomena may be due to the intricate oxidative mechanism of pyrogallol and the polyfunctions of the model compounds acting as mimics of polypheol oxidase and Fenton's reagent as well as Lewis acidity of the metals in them. Therefore, the method of pyrogallol autoxidation can not be used to assay SOD activity.