白毫早鲜叶茶多酚氧化酶酶学特性

Features of Polyphenol Oxidase in Baihaozao Fresh Tea Leaves

为了解白毫早鲜叶中的PPO酶学特性,采用分光光度法,研究底物浓度、温度和pH对白毫早鲜叶PPO活性的影响以及PPO的热稳定性。结果表明:PPO活性随着温度、pH的增大呈先增大后减少的钟形曲线关系,其最适温度为40℃,最适pH为6.0;其耐热性较强,于80℃处理1min可钝化酶活力。酶促反应在温度37℃、pH 5.6柠檬酸-磷酸缓冲液、邻苯二酚为底物条件下,Km值和Vmax分别为0.621 7mol/L和4.46U/min。

In order to explore the enzymatic characteristics of PPO in Baihaozao fresh tea leaves, spectrophotometric method was employed to study the effects of substrate concentration,temperature and pH on PPO activity and its thermal stability.Results：PPO activity first increased and then decreased with temperature and pH increasing.The suitable temperature and pH was 40℃ and 6.0 respectively;The thermal stability was strong,and the enzyme activity could be passivated after treated at 80℃ for one minute.Values of Km and Vmax were respectively 0.6217 mol/L and 4.46 U/min under the following conditions：temperature 37℃,pH 5.6 and substrate of catechol.