PDF(Pubmed)
Abstract：
(R)-mandelic acid is an industrially important chemical, especially used for producing antibiotics. Its chemical synthesis often uses highly toxic cyanide to produce its racemic form, followed by kinetic resolution with 50% maximum yield. Here we report a green and sustainable biocatalytic method for producing (R)-mandelic acid from easily available styrene, biobased L-phenylalanine, and renewable feedstocks such as glycerol and glucose, respectively. An epoxidation-hydrolysis-double oxidation artificial enzyme cascade was developed to produce (R)-mandelic acid at 1.52 g/L from styrene with > 99% ee. Incorporation of deamination and decarboxylation into the above cascade enables direct conversion of L-phenylalanine to (R)-mandelic acid at 913 mg/L and > 99% ee. Expressing the five-enzyme cascade in an L-phenylalanine-overproducing E. coli NST74 strain led to the direct synthesis of (R)-mandelic acid from glycerol or glucose, affording 228 or 152 mg/L product via fermentation. Moreover, coupling of E. coli cells expressing L-phenylalanine biosynthesis pathway with E. coli cells expressing the artificial enzyme cascade enabled the production of 760 or 455 mg/L (R)-mandelic acid from glycerol or glucose. These simple, safe, and green methods show great potential in producing (R)-mandelic acid from renewable feedstocks.
摘要：
(R)-扁桃酸是一种重要的工业化学品,特别是用于生产抗生素。它的化学合成通常使用剧毒氰化物来产生它的外消旋形式，然后是动力学分辨率，最大产率为50％。在这里，我们报告了一种绿色和可持续的生物催化方法，用于从容易获得的苯乙烯生产（R）-扁桃酸，生物基L-苯丙氨酸，和可再生原料，如甘油和葡萄糖，分别。开发了环氧化-水解-双氧化人工酶级联反应，从苯乙烯中以1.52g/L生产（R）-扁桃酸，ee>99％。将脱氨基和脱羧结合到上述级联中能够使L-苯丙氨酸以913mg/L和>99%ee直接转化为(R)-扁桃酸。在过量生产L-苯丙氨酸的大肠杆菌NST74菌株中表达五酶级联导致从甘油或葡萄糖直接合成（R）-扁桃酸，通过发酵提供228或152毫克/升的产品。此外，表达L-苯丙氨酸生物合成途径的大肠杆菌细胞与表达人工酶级联的大肠杆菌细胞的偶联使得能够从甘油或葡萄糖产生760或455mg/L(R)-扁桃酸。这些简单的，安全,和绿色方法在从可再生原料生产（R）-扁桃酸方面显示出巨大的潜力。
