商品果胶酶(Aspergillus niger)的催化动力学研究  

Study on catalytic kinetics of commercial pectinase from Aspergillus niger

作　　者：林建城[1] 杨文杰[1] 朱丽华[1] 王志鹏[1] 陈国强[1] 

机构地区：[1]莆田学院环境与生命科学系,福建莆田351100

出　　处：《甘肃农业大学学报》2006年第4期81-85,共5页Journal of Gansu Agricultural University

基　　金：莆田市科技计划项目(2005N12)资助;福建省教育厅科技项目(JA05320)资助.

摘　　要：研究了商品果胶酶的催化动力学特性,结果表明：果胶酶的最适pH为3.8，最适温度为50℃，酶在pH3．4～4.2区域较稳定，在pH＞4．5与pH＜3．0下很快失活；酶在50℃以内具有较好的热稳定性，温度升高，酶的热稳定性下降，65℃下热变性2h，酶活力降低80％．酶促反应动力学符合米氏双曲线方程，测得果胶酶水解果胶的米氏常数Km=（5.16±0.13）mg／mL，最大反应速度Vmax=（2．73±0.02）μg／（mL·min）．Na^＋和K^＋对酶活力没有任何效应，0．1mmol／L Ca^2＋可使酶活力提高22.8％，5．0mmol／L Zn^2＋对果胶酶活力的抑制达到17．4％，M^2＋、Mn^2、Co^2＋、Hg^2＋和Ag^＋对果胶酶活力影响不大，Cu^2＋和Fd^3＋对果胶酶活力影响较大，浓度为5．0mmol／L时，对果胶酶的抑制可分别达到88.9％和100％．The characteristics in ca determineded. The results showed that talytic kinetics of commercial pectinase from Aspergillus niger were the optimum pH and optimum temperature of the enzyme for the hydrolysis of pectin （enzyme substrate）were pH 3.8 and 50 ℃, respectively. The behavior of the enzyme during hydrolysis of pectin followed Michaelis-Menten kinetics,with Km= 5. 16±0. 13 mg ·mL^-1 and Vmax =2.73±0.02μg·mL^-1·min^-1 ,at pH 3.8 and 50℃. The stability of the enzyme was investigated,and the results showed that the enzyme was stable in a pH range from 3.4 to 4.2 and at temperatures〈50℃. The effects of metal ions on the enzyme were also studied. Na^＋ and K^＋ had no influence on enzyme activity. Ca^2＋ in the concentration of 0.1 mmol/L increase activity of the enzyme, while Mg^2＋ , Mn^2＋ , Co^2＋ , Ni^2＋ , Hg^2＋ ,Ag^＋ ,Zn^2＋ ,Cu^2＋ and Fe^3＋ showed various degrees of inhibitory effects on the enzyme in the concentration of 5.0 mmol/L,among which Zn^2＋ in the concentration of 5.0 mmol/L inhibited activity of the enzyme by 17.4 %,and Cu^2＋ by 88.9 %, Fe^3＋ by 100 %.

关 键 词：果胶酶 催化动力学 酶活力 稳定性 金属离子 

分 类 号：Q356.1[生物学—遗传学]