摘要
利用酿酒酵母作为生物催化剂合成L-苯基乙酰基甲醇(L-Phenylacetylcarbiol,L-PAC)的过程中,通过加入有机溶剂(辛醇)形成两相体系,可改善底物和产物的溶解度,以减少对细胞内丙酮酸脱羧酶(PDC)的强烈抑制和钝化作用,从而促进L-PAC产量的提高。实验结果表明,两相体系合成L-PAC的最佳条件为活化60 min,苯甲醛的起始浓度940 mmol/L,丙酮酸钠的起始浓度460 mmol/L,葡萄糖的含量8%,水醇两相体积比为3∶1,且加入一定量的甘油时,L-PAC产量可达在醇相中24.1 g/L和水相中3.7 g/L,比单一水相体系高出1.8倍。
L-Phenylacetylcarbinol （L-PAC） , a key pharmaceutical precursor for L-ephedrine synthesis, was produced from pyruvate and benzaldehyde using whole cells pyruvate deearboxylase （PDC） from Saccharomyces cerevisiae in an aqueous/organic two-phase systems. In a solvent screen, octanol was identified as the most suitable solvent for PAC production in the two-phase systems. Using the systems have been evaluated for improved the solubility of substrate benzaldehyde and product PAC. The high partitioning coeffi- cient of the toxicsubstrate benzaldehyde in octanol allowed delivery of large amounts of benzaldehyde into the aqueous phase. PDC catalyzed the biotransformation of benzaldehyde and pyruvate into PAC in the aqueous phase, and continuous extraction of PAC into the octanolphase further minimized enzyme inactivation and inhibition. It is clear that the results achieved with enhancing PAC production. For the two-phase system with a 3 ： 1 phase ratio, 60minutes activation time, 940 mmol/L benzaldehyde, 460 mmol/L sodium pyruvate and 8% glucose,24.1 g/L PAC was produced in the octanol phase and 3.7 g/L in the aqueous phase with adding a certain amount of glycerol. By comparison with previously published data by our group utilizing whole cells of yeast for the traditional fermentation process aqueous single-phase system without octanol（ 15 g/L PAC ,200 mmol/L benzaldehyde） ,in an octanol/aqueous two-phase systems significantly PAC concentrations can be achieved a 1.8-fold higher, as well as whole cells PDC could toleratea 9.5-fold improvement on the initial benzaldehyde concentration. Recent progress in enzymatic PAC production has established the need for low cost biocatalyst preparation while maintaining the high concentrations, productivities and yields. Whole cell PDC showed higher stability towards temperature and more facilitation of product recovery in comparison with partially purified preparations. The use of whole cell PDC fromSaccharomyces cerevisiae was therefore evaluated in an aqueous/octanoltwo-phase systems.
出处
《药物生物技术》
CAS
CSCD
2012年第4期296-298,303,共4页
Pharmaceutical Biotechnology
关键词
生物转化
辛醇/水两相体系
苯甲醛
丙酮酸脱羧酶
L-苯基乙酰基甲醇
全细胞
Biotransformation, Aqueous/octanol two-phase system, Benzaldehyde, Pyruvate decarboxylase, L-phenylacetylcarbinol,Whole cells
