红薯过氧化物酶的纯化与性质测定

以红薯块根为材料,对红薯中的过氧化物酶进行提取、分离、纯化并测定其性质。结果表明:经40%～80%饱和度的硫酸铵分级分离、Sephadex G-100凝胶过滤、Concanavalin A亲和层析三个步骤,获得纯化的红薯过氧化物酶,酶纯化倍数为26.56倍,回收率0.92%,比活性3841.80 U/mg,SDS-PAGE电泳显示酶分子量为23 kDa。红薯过氧化物酶以愈创木酚为底物时λmax=470 nm,Km=3.031 mmol/L,酶的最适pH值为5.0,最适温度是35℃。酶的热稳定性较高,60℃保温20 min,残存相对活性为72.40%;酶的低温贮存稳定性很高,0～4℃冰箱中贮存20 d后,残存相对活性为97.28%。

Purification and Property Determination for Peroxidase in Sweet Potato

The tuber of sweet potato was used as material.The peroxidase in sweet potato was extracted,separated and purified and its properties were determined.The results indicated that by means of 40~80% ammonium sulfate precipitation,Sephadex G-100 gel filtration and affinity chromatography with concanavalin A,the purified peroxidase were obtained from sweet potato.Its purification fold,recovery rate and specific activity were 26.56,0.92% and 3 841.80 U/mg,respectively.SDS-PAGE electrophoresis showed the molecular mass of the peroxidase was 23 kDa.With guaiacol as substrate,λmax=470 nm,Km=3.031 mmol/L,the optimum conditions for the peroxidase were temperature of 35℃ and pH of 5.0.The peroxidase showed a high thermal stability,it remained 72.40% of the original activity after it had been treated at 60℃ for 20 min.It also showed very high storage stability at low temperature,and it remained 97.28% of the original activity after it had been treated at 0~4℃ for 20 days.