中文摘要：

为深入了解沙门氏菌草酰乙酸脱羧酶的生化特性及功能,将该酶基因克隆到表达载体中,转入大肠杆菌中诱导表达,表达产物经monomeric avidin-Sepharose亲和层析分离纯化,获得了纯的沙门氏菌草酰乙酸脱羧酶。结果表明：纯化后的草酰乙酸脱羧酶经SDS-PAGE检测,呈现3条蛋白谱带,相对分子质量分别为65×103、46×103、8.8×103左右;该酶不耐高温,50℃温浴1h后活力几乎完全丧失;其最适pH为6.0左右;1mmol·L-1Zn2＋、0.5mmol·L-1草酸和20mmol·L-1丙酮酸几乎完全抑制该酶的活力,10～20mmol·L-1NaCl对该酶有明显激活作用,但200～500mmol·L-1的NaCl对该酶却有明显抑制作用。

英文摘要：

In order to know the biochemical characterization and function of oxaloacetate decarboxylase from Salmonella typhimurium,the gene of oxaloacetate decarboxylase was cloned and expressed in Escherichia coli.The product was purified by affinity chromatography on monomeric avidin-Sepharose column,and shown 95% pure on SDS-PAGE.It was shown to be composed of three subunits with relevant molecular weight around 65 × 103,46 × 103,8.8 × 103 corresponding to the predicated molecular weight of alpha,beta and gamma subunits respectively by SDS-PAGE.The holo-enzyme was unstable to heat,the activity of oxaloacetate decarboxylase was abolished at 50 ℃ for 1 h;the optimum pH was about 6.0.The activity of oxaloacetate decarboxylase was almost inhibited completely by 1 mmol·L-1 Zn2 ＋ and 0.5 mmol·L-1 oxalate and 20 mmol·L-1 pyruvate,10-20 mmol·L-1 NaCl had obvious activation,but 200-500 mmol·L-1 NaCl had obvious inhibition for the catalytic activity of oxaloacetate decarboxylase.