近江牡蛎铜锌超氧化物歧化酶的纯化及部分性质研究

Purification and Characterization of Copper Zinc Superoxide Dismutase from Ostrea rivularis Gould

经６５℃加热，硫酸铵分级沉淀，ＳｅｐｈａｄｅｘＧ－１００凝胶过滤和ＤＥ－５２柱层析，从近江牡蛎（ＯｓｔｒｅａｒｉｖｕｌａｒｉｓＧｏｕｌｄ）软体部分提纯了铜锌超氧化物歧化酶（Ｃｕ，Ｚｎ－ＳＯＤ）．对其理化性质鉴定表明，用此法纯化的酶纯度均一．该酶系由两个相同亚基组成的二聚体，分子量２７．９ｋＤ．该酶的紫外吸收峰在２７２．５ｎｍ，红外光谱表现出其氨基酸组成特征，与猪血ＳＯＤ存在差异．该酶在不同的升温速率下及经不同浓度的Ｈ２Ｏ２处理后的稳定性与猪血ＳＯＤ不同．其氨基酸组成与不同来源的同类酶存在差异．

Copper Zinc superoxide dismutase (Cu,Zn SOD) was purified from Ostrea rivularis Gould by short time hemogenating with sodium chloride at low concentration,heat treatment at 65℃ for 15 min,and dialysis in the presence of Cu 2+ ,following precipitation with ammonium sulfate,Sephadex G 100 filtration and DE 52 chromatography with a yield of 37 8% by a purification factor of 511.The investigation of physiochemical properties showed that the SOD obtained by this method was homogeneously pure.Its molecular weight was about 27 9 kD composed of two equally sized subunits.It had a fairly good thermostability up to at least 58 4℃.The ultraviolet absorption peak of the enzyme was found at 272.5 nm,and its infrared spectra,though,different from those of porcine RBC SOD,were in accordance with its characteristic of its amino acid composition.Differential scanning calorimetry (DSC) analysis indicated that the stability of the purified enzyme was different from that porcine RBC SOD when treated at various heating rates or after being treated with H 2O 2 of various concentrations.Its amino acid composition was different from similar enzymes reported previously.