Selective Hydrolysis of Aliphatic Dinitriles to Monocarboxylic Acids by a Nitrilase from Arabidopsis thaliana
作者:Franz Effenberger、Steffen Oßwald
DOI:10.1055/s-2001-17523
日期:——
The hydrolysis of a variety of dinitriles including α,Ï-dicyanoalkanes 1, β-substituted glutaronitriles 5, and γ-cyanopimelonitrile 7 with a recombinant plant nitrilase from Arabidopsis thaliana, expressed in E. coli, is described. Conversion rate and selectivity of the hydrolysis of dinitriles 1a-f to Ï-cyanocarboxylic acids 2a-f depend on the chain length. The enzyme activity markedly increases from malononitrile (1a) to octanedinitrile (1f). The selectivity, however, does not correlate with the rates. Up to a chain length of 6 C-atoms, the cyanocarboxylic acid is the only product, even at complete conversion of the starting material. Pimelonitrile (1e) is hydrolyzed to the cyanocarboxylic acid 2e without formation of diacid (<1%) up to 73% conversion. Glutaronitriles 5a-c were also hydrolyzed to the corresponding cyanobutanoic acids 6a-c with perfect selectivity. The nitrilase hydrolyzes exclusively the primary cyano group of 7 to give 3,5-dicyanoheptanoic acid (8a), whereby the selectivity is slightly reduced compared to the unsubstituted pimelonitrile (1e). If the hydrolysis is terminated at conversions ≤90%, pure 8a can be isolated in 72% yield (92% referred to conversion). After esterification of 8a to the methyl ester 8b, only the 5-cyano group but not the ester function was hydrolyzed enzymatically to give cyanoheptanedioic acid monoester (10).
描述了使用来自阿拉伯芥(Arabidopsis thaliana)的重组植物腈水解酶在大肠杆菌中表达,对多种二腈(dinitriles)进行水解的过程,这些二腈包括α,ω-二氰烷烃1、β-取代的戊二腈5和γ-氰基庚腈7。二腈1a-f转化为ω-氰基羧酸2a-f的水解转化率和选择性依赖于链长。从丙二腈(1a)到辛烯二腈(1f),酶活性显著增加。然而,选择性与转化速率并不相关。对于6个碳原子以下的链长,氰基羧酸是唯一的产品,即使起始材料完全转化。庚腈(1e)在转化率达到73%时,仅被水解为氰基羧酸2e,而未形成二酸(<1%)。戊二腈5a-c也被水解为相应的氰基丁酸6a-c,具有完美的选择性。腈水解酶专门水解7的原料氰基,生成3,5-二氰基庚酸(8a),相比于未取代的庚腈(1e),选择性略有降低。如果在转化率≤90%时终止水解,可以以72%的产率(转化率92%)单独分离出纯8a。在将8a酯化为甲酯8b后,只有5-氰基基团而不是酯功能被酶催化水解,生成氰基庚二酸单酯(10)。