马铃薯酪氨酸酶的性质  

Some properties of potato tyrosinase

作　　者：胡源[1] 刘克武[1] 喻东[1] 刘鑫[1] 黄新河[1] 唐成康[1] 姜骅[1] 季雯娟[1] 

机构地区：[1]四川大学生命科学学院,四川成都610064

出　　处：《化学研究与应用》2005年第1期55-57,共3页Chemical Research and Application

摘　　要：用硫酸铵分级沉淀、DEAE SepharoseFF和SephadexG 150柱层析,从马铃薯中分离纯化出酪氨酸酶,纯化倍数50,比活170.03U mg蛋白。SDS PAGE检测呈现一条带。分子量42KD。酶的最适pH7 5,最适温度30℃。该酶具有单酚酶和二酚酶活性,其中以邻苯二酚为底物活性最高,以L DOPA为底物Km值为3 70mmol·L-1。Hg2+、Zn2+、Fe2+为激活剂,K+、Ga2+、Mg2+是抑制剂。Ga2+为非竞争性抑制,抑制常数ki为116 8mmol·L-1,K+为竞争性抑制,抑制常数ki为10mmol·L-1。Tyrosinase from potato was purified to electrophoretic homogeneity by salting-out,DEAE-Sepharose FF and Sephadex G-150.The specific activity was 170.03U/mg.The molecular weight is 42KD with SDS-PAGE.Ezymatic activity of Tyrosinase against L-DOPA was optimal at pH7.5 and 30℃.The enzyme exhibited monophenols and diphenols with diffeneent substrates and showed high substrate specificity towards catechol.The Km value of the enzyme for L-DOPA was 3.70mM.The enzyme was sensitive to metal ions.Its activity is strongly enhanced by Hg^(2+),Zn^(2+),Fe^(2+)and inhibited by K^+,Ga^(2+),Mg^(2+),Ga^(2+) and K^+was selected for determining types of inhibition and the result showed that KCl was a competitive inhibitor,with inhibition constant of 10 mmol/L,GaCl_2 was a noncompetitive inhibitor,with inhibiton constant of 11.68 mmol/L.

关 键 词：马铃薯 酪氨酸酶 抑制 

分 类 号：O629.8[理学—有机化学]