曲酸对蘑菇多酚氧化酶的抑制作用  

Inhibitory Effect of Kojic Acid on Mushroom Polyphenol Oxidases

作　　者：吕艳芳[1,2] 陈培丽[1] 李颖畅[1] 杨铭铎[2] 林洪[3] 励建荣[1] 

机构地区：[1]渤海大学食品科学与工程学院,辽宁锦州121013 [2]哈尔滨商业大学食品工程学院,哈尔滨150076 [3]中国海洋大学食品学院,山东青岛266100

出　　处：《中国食品学报》2017年第4期30-36,共7页Journal of Chinese Institute Of Food Science and Technology

基　　金："十二五"国家科技支撑计划项目(2012BAD29B06);辽宁省食品安全重点实验室开放课题(LNSAKF2011033)

摘　　要：以蘑菇多酚氧化酶(PPO)为原料,研究不同浓度曲酸对PPO活性的影响,并对不同活性酶参与的反应体系动力学参数(K_m,V_(max))进行测定,最后应用FT-IR分析不同浓度曲酸处理的PPO酶的二级结构。结果表明:随着作用PPO曲酸浓度的增加,PPO的剩余酶活逐渐降低,当曲酸浓度达到0.3 mmol/L时,PPO剩余酶活仅为原酶活性的7.12%;当反应体系酶活逐渐减小时,反应速率也减小,反应体系白度值和ΔE值逐渐增加,说明曲酸抑制了多酚氧化酶的活性,反应体系褐变程度降低;被不同浓度曲酸处理的PPO参加的反应体系,随着底物(邻苯二酚)浓度的增加,将反应速率与底物浓度关系以Lineweaver-Burk双倒数法作图,结果显示:PPO的Km值逐渐增加,Vmax趋于相等,符合竞争性抑制剂作用于酶的特点。选取酰胺Ⅲ带FT-IR光谱数据,分析被不同浓度曲酸处理的PPO二级结构类型变化,结果α-螺旋、β-转角含量增加,β-折叠和无规则卷曲含量减少。This paper studied the effect of different concentrations of kojie acid on the activity of polyphenol oxidase from mushroom. The kinetic parameters （Kin, Vmax） of reaction system involved in the activity of different enzymes were determined. The secondary structures of PPO treated with different concentrations of kojic acid were investigated using FI-IR. The results showed the residual activity of PPO decreased gradually with increasing kojic acid concentration. When the concentration of kojic acid was 0.3 mmol/L, the residual activity of PPO was only 7.12%. Enzyme activity of system and reaction rate decreased gradually, while the white value and AE increased, which suggested that kojic acid re- strained the activity of PPO, consequently, led to the reduced browning degree. In reaction system treated with different concentrations kojic acid of PPO, Lineweaver-Burk including reaction rate and substrate concentration plots demonstrated that as the substrate concentration （catechol） increasing, the K,, values of PPO increased gradually and the Vmax remained unchanged, consistent with the characteristics of competitive inhibitors acting on enzymes. The Amide m FT-IR Spectrum data reflected the situation of treated with different concentrations kojic acid of PPO, the content of α-helix and β-turns increased, while β-sheet and random coil decreased.

关 键 词：曲酸 多酚氧化酶 剩余酶活 抑制作用 褐变 

分 类 号：TS201.25[轻工技术与工程—食品科学]