西南冷凉高地不同品种马铃薯多酚氧化酶酶学特性及其抑制剂的研究

Study on the enzymatic characteristics and inhibitors of polyphenol oxidase from different potato varieties in cold highland of Southwest China

以西南冷凉高地选育的5个马铃薯品种为试验材料,对比了不同品种马铃薯中多酚氧化酶的酶学性质差异,测定了几种抑制剂对酶活力的影响。结果表明,温度、pH、底物浓度和抑制剂对马铃薯多酚氧化酶的酶活均有显著影响,其中品种ZT032多酚氧化酶的最适pH为6.0,ZT29-73和ZT43-14的最适pH为6.5,ZT10-6和ZT02的最适pH为7.0;ZT43-14多酚氧化酶的最适反应温度为20℃,ZT032、ZT29-73和ZT02的最适反应温度为25℃,ZT10-6的最适反应温度为30℃。5个品种马铃薯多酚氧化酶的热稳定性均较差,最适底物浓度均为0.1 mol/L。品种ZT29-73、ZT43-14和ZT02的V_(max)/K_(m)比值为50,表明其与底物邻苯二酚具有较好的催化效果,优于ZT10-6和ZT032。通过添加不同抑制剂对多酚氧化酶酶活的作用效果也不同,其中亚硫酸氢钠对5个马铃薯品种的多酚氧化酶均具有较好的抑制效果,其次是L-半胱氨酸和抗坏血酸,EDTA-2Na和柠檬酸的效果较差。本研究为高原特色马铃薯加工利用时的品种和抑制酶促褐变添加剂的选择提供了参考依据。

Five potato varieties selected from the cold highland of Southwest China were used as experimental materials to compare the enzymatic properties of polyphenol oxidase from different potato varieties and determine the effects of several inhibitors on the enzyme activities.The results showed that temperature,pH,substrate concentration and inhibitors had significant effects on the activity of PPO,among which zt032 was the best.The optimum pH of PPO was 6.0,the optimum pH of ZT29-73 and ZT43-14 was 6.5,the optimum pH of ZT10-6 and zt02 was 7.0,the optimum reaction temperature of ZT43-14 was 20℃,the optimum reaction temperature of ZT032,ZT29-73 and ZT02 was 25℃,and the optimum reaction temperature of ZT10-6 was 30℃.The results showed that the thermal stability of PPO from potato varieties was poor,and the optimal substrate concentration was 0.1mol/L.The V_(max)/km ratio of ZT29-73,ZT43-14 and ZT02 was 50,indicating that they had better catalytic effect with catechol than ZT10-6 and ZT032.Among them,sodium bisulfite had a good inhibitory effect on polyphenol oxidase of five potato varieties,followed by L-cysteine and ascorbic acid,and edta-2na and citric acid had a poor effect.This study provides a reference for the selection of potato varieties and additives to inhibit enzymatic browning in plateau characteristic potato processing and utilization.