可溶态和膜结合态马铃薯多酚氧化酶的性质对比

Comparison of Properties of Soluble and Membrane Bound Potato Polyphenol Oxidase

摘要:

以大西洋马铃薯为原料，制备可溶态（sPPO）和膜结合态（mPPO）多酚氧化酶，并对两种粗酶液的酶学性质进行研究。结果表明，sPPO最适反应温度为35 ℃，最适pH值为7，mPPO最适反应温度为30 ℃，最适pH值为7。以焦性没食子酸、邻苯二酚为底物时，sPPO的米氏常数（Km）分别为10.04 mmol/L和24.00 mmol/L，最大反应速度（Vmax）值分别为443 U/(mL·min)和965 U/(mL·min)，mPPO的米氏常数（Km）分别为4.98 mmol/L和48.04 mmol/L，最大反应速度（Vmax）值分别为299 U/(mL·min)和912 U/(mL·min)，且对焦性没食子酸的催化效果优于邻苯二酚。6种抑制剂对比发现，Na2SO3对sPPO活性的抑制效果最好，Vc对mPPO活性的抑制效果最好。sPPO和mPPO的酶学特性有一定的差异，对马铃薯制品加工过程中酶促褐变的控制具有指导意义。

Abstract:

Atlantic potato was used as raw material to prepare soluble (sPPO) and membrane bound (mPPO) polyphenol oxidase. The results showed that the optimal reaction temperature of sPPO was 35 ℃, the optimal pH value was 7. The optimal reaction temperature of mPPO was 30 ℃, and the optimal pH value was 7. When pyrogallic acid and catechol were used as substrates, the Km values of sPPO were 10.04 mmol/L and 24.00 mmol/L, respectively, and the Vmax values were 443 U/mL·min and 965 U/mL·min, respectively. The Km values of mPPO were 4.98 mmol/L and 48.04 mmol/L, respectively, and the Vmax values were 299 U/mL·min and 912 U/mL·min, respectively, and the catalytic effect of pyrogallic acid was better than that of catechol. The comparison of 6 inhibitors showed that Na2SO3 had the best inhibition effect on sPPO activity and Vc had the best inhibition effect on mPPO activity. The enzymatic characteristics of sPPO and mPPO were different. The results will be provide a guiding significance for the control of enzymatic browning in the processing of potato products.