Abstract Objectives Chiral 2-hydroxycarboxylic acids and 2-hydroxycarboxamides are valuable synthons for the chemical industry. Results The biocatalytic syntheses of ( R )-mandelic acid and ( R )-mandelic acid amide by recombinant Escherichia coli clones were studied. Strains were constructed which simultaneously expressed a ( R )-specific oxynitrilase (hydroxynitrile lyase) from the plant Arabidopsis thaliana together with the arylacetonitrilase from the bacterium Pseudomonas fluorescens EBC191. In addition, recombinant strains were constructed which expressed a previously described acid tolerant variant of the oxynitrilase and an amide forming variant of the nitrilase. The whole cell catalysts which simultaneously expressed the ( R )-specific oxynitrilase and the wild-type nitrilase transformed in slightly acidic buffer systems benzaldehyde plus cyanide preferentially to ( R )-mandelic acid with ee-values > 95%. The combination of the ( R )-specific oxynitrilase with the amide forming nitrilase variant gave whole cell catalysts which converted at pH-values ≤ pH 5 benzaldehyde plus cyanide with a high degree of enantioselectivity (ee > 90%) to ( R )-mandelic acid amide. The acid and the amide forming catalysts also converted chlorinated benzaldehydes with cyanide to chlorinated mandelic acid or chlorinated mandelic acid amides. Conclusions Efficient systems for the biocatalytic production of ( R )-2-hydroxycarboxylic acids and ( R )-2-hydroxycarboxamides were generated.

中文翻译：

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通过表达 (R)-特异性氧腈酶和芳基乙腈酶的重组大肠杆菌菌株合成 (R)-扁桃酸和 (R)-扁桃酸酰胺

摘要 目的手性2-羟基羧酸和2-羟基羧酰胺是化学工业中有价值的合成子。结果对重组大肠杆菌克隆生物催化合成(R)-扁桃酸和(R)-扁桃酸酰胺进行了研究。构建的菌株同时表达来自植物拟南芥的 (R) 特异性羟腈酶（羟腈裂解酶）以及来自荧光假单胞菌 EBC191 细菌的芳基乙腈酶。此外，构建了重组菌株，其表达先前描述的羟腈酶的耐酸变体和腈水解酶的酰胺形成变体。同时表达( R )-特异性腈水解酶和野生型腈水解酶的全细胞催化剂在微酸性缓冲系统苯甲醛加氰化物中优先转化为( R )-扁桃酸，ee值> 95%。( R ) 特异性羟腈酶与形成酰胺的腈水解酶变体的组合产生了全细胞催化剂，其在 pH 值≤ pH 5 苯甲醛加氰化物时具有高度的对映选择性 (ee > 90%) 转化为 ( R )-扁桃酸酰胺。酸和酰胺形成催化剂还用氰化物将氯化苯甲醛转化为氯化扁桃酸或氯化扁桃酸酰胺。结论产生了用于(R)-2-羟基羧酸和(R)-2-羟基甲酰胺的生物催化生产的有效系统。