超氧化物歧化酶全酶和脱辅基酶胍变性时失活与去折叠的比较研究

利用紫外差吸收光谱和荧光发射光谱等监测手段研究天然铜锌ＳＯＤ（ｈｏｌｏ－ＳＯＤ）和脱铜锌ＳＯＤ（ａｐｏ－ＳＯＤ）在不同浓度胍溶液中的去折叠及活力变化．结果表明ｈｏｌｏ－ＳＯＤ和ａｐｏ－ＳＯＤ分别在４．０和２．０ｍｏｌ／Ｌ胍溶液中去折叠，而分别在２．０和０．５ｍｏｌ／Ｌ胍溶液中其构象尚未发生明显改变时活性几乎完全丧失．提示金属离子对维持酶的整体及活性部位构象具有重要作用，脱去金属离子的酶分子的构象特别是活性部位的构象更易受到变性剂的破坏．

A Comparison of Inactivation and Unfolding of Holo and Apo Superoxide Dismutase during Guanidine Denaturation

The unfolding process and the activity change of Cu,Zn superoxide dismutase (holo SOD) and metal depleted SOD(apo SOD) in guanidine solutions of diffrent concentrations was studied by fluorescence and ultraviolet difference spectroscopic methods.The results showed that holo and apo SOD forms were completely unfolded by GuHCl at 4 0 and 2 0 mol/L,completely inactivated by GuHCl at 2 0 and 0 5 mol/L,respectively.Results supposed that the presence of metal ion helps to keep the conformation of the active site and molecular region of the enzyem.The conformation of the metal depleted SOD,particularly of its active site,was easier to be disturbed by denaturants than that of the holo SOD.