摘要
花生体内控制多胺生物合成的主要酶是ADC主要定位于代谢活跃的分生组织内。部分纯化(13倍)的酶最适底物是L-Arg,Km值和Vmax依次为0.56mmol/L、0.66μlCO2/mgprotein.min。反应最适pH和温度为8~8.5和40~45℃。该酶对热、乙醇、脲稳定性差。0.8mmol/LPLP(磷酸吡哆醛)可提高酶活性21%,DTT(二硫苏糖醇)、ME(巯基乙醇)提高酶的稳定性,对氯苯汞甲酸酯抑制酶活70%。说明ADC可能以PLP为辅酶,活性中心含有巯基。6-BA、GA3可明显提高酶活性。二价金属离子对酶活性影响很小。Spd(亚精胺)、Spm(精胺)和Put(腐胺)均不同程度地降低酶活性,多胺的生物合成途经中可能存在反馈调节机制。
Arginine decarboxylase(EC4.1.1.19),a enzyme in polyamine biosynthesis,was found to be localized in apical meristem in peanut seedling.The partially purified enzyme(about 13 fold)readily decarboxylated L arginine,its Km and Vmax value was 0.56mmol/L and 0.66μlCO 2/mg protein·min respectively.Stability of enzyme to temperature,ethyl and urea was lower.Addition of 0.8mmol/L PLP to the reaction mixture caused an increase in the activity of the enzyme by about 21%.DTT and ME caused an increase in stability of the enzyme,p chloromercuribenzoate strongly inhibited the specific activity of the enzyme(70% inhibition).It is suggested that PLP acted as a cofactor of the enzyme and the SH group is involved in enzyme activity.The enzyme activity is stimulated by 6 BA and GA 3.The requirement of divalent metal ions is not evident for the enzyme activity.Inhibition by spermidine,spermine and putrescine suggests possible feed back mechanism in the pathway of polyamine biosynthesis.
出处
《山东农业大学学报(自然科学版)》
CSCD
1997年第1期21-26,共6页
Journal of Shandong Agricultural University:Natural Science Edition
关键词
精氨酸脱羧酶
纯化
特性
花生
幼苗
Arginine decarboxylase
partially purification
characterization
peanut seedling