【摘要】 酪氨酸脱羧酶能以L-酪氨酸为底物脱羧生成酪胺。该文利用pET28a为载体在宿主细胞E.coli BL21(DE3)中重组表达了短乳杆菌来源的酪氨酸脱羧酶,并研究了其酶学性质,考察了起始pH、温度、辅酶、底物浓度等因素对酶活的影响。结果表明,酪氨酸脱羧酶重组表达成功,酶促反应工艺为:在1 mL转化液中含有0.18 g L-酪氨酸,0.02 g湿菌体,0.2 mol/L的醋酸缓冲溶液和0.2 mmol/L的5’-磷酸吡哆醛,40℃,pH=5.5,反应7 h,L-酪氨酸的摩尔转化率达到99%。酪氨酸脱羧酶酶活为29.2 U/g,Km值和Vmax为0.71 mmol/L和9.31mol/(L·min·g)。更多还原

【Abstract】 Tyrosine decarboxylase( TDC) is an enzyme that is used to catalyze the decarboxylation of Ltyrosine to produce tyramine and CO2. In this study,the vector pET28a was used to recombinantly express the tdc gene from Lactobacillus brevis in Escherichia coli BL21( DE3). Several influencing factors of the enzyme reaction,including pH,temperature,coenzyme,and concentration of substrate,were all investigated. The results indicate that the recombinant tyrosine decarboxylase was successfully expressed and the reaction was optimal at pH = 5. 5 and 40 ℃,0. 02 kg /L cells,0. 2 mol /L acetic acid buffer solution( pH = 5. 5),0. 2 mmol /L 5-pyridoxal phosphate and 0. 18 kg /L L-tyrosine. After 7hours,the mole conversion rate of L-tyrosine was up to 99%. TDC’s enzyme activity was 29. 2 U /g. The Kmand Vmaxvalues of TDC were 0. 71 mmol /L and 9. 31 mol /( L·min·g).更多还原