乳酸脱氢酶与葡萄糖脱氢酶偶联催化合成D-苯基乳酸

Synthesis of D-phenyllactic acid catalyzed by coupled lactate dehydrogenase and glucose dehydrogenase

D-苯基乳酸(D-phenyllactic acid,D-PLH)是一种理想的天然防腐剂,具有广谱抗菌活性。实验构建了1株乳酸脱氢酶重组大肠杆菌E.coli BL21(DE3)/pET28a-ldh,并对其诱导表达条件进行了优化。在最优条件下(当OD_(600)值达到0.8时,添加乳糖8 g/L,在28℃下诱导8 h),重组乳酸脱氢酶比酶活达到298.8 U/g(干菌体)。建立了乳酸脱氢酶和葡萄糖脱氢酶双酶偶联催化体系,并应用于苯丙酮酸钠还原生成D-苯基乳酸。对反应条件,包括温度、pH值、两重组菌质量比和葡萄糖浓度进行了优化,在最优反应条件下,D-苯基乳酸累积质量浓度达到18.03 g/L,时空产率为162.27 g/(L·d),ee>99%。双酶耦联催化体系是D-苯基乳酸合成的有效工具,显示了良好的应用前景。

D-phenyllactic acid is an ideal natural antimicrobial compound with broad spectrum activity. A lactate dehydrogenase recombinant bacteria Escherichia coli BL21(DE3)/pET28 a-ldh was constructed, and its activity under optimized conditions reached 298.8 U/g dry cell weight. A lactate dehydrogenase and glucose dehydrogenase coupled catalysis system was established and applied in reducing sodium pyruvate to produce D-phenyllactic acid. The reaction conditions were optimized, including temperature, pH, mass ratio of two recombinant bacteria, and glucose concentration. Under the optimal reaction condition, D-phenyllactic acid accumulated up to 18.03 g/L with ee >99%, and the space-time yield reached 162.27 g/(L·d). Therefore, this catalytic system is effective to synthesize D-phenyllactic acid and has shown a good application prospect.