Characterisation of nitrilase and nitrile hydratase biocatalytic systems.

D Brady, A Beeton, J Zeevaart, C Kgaje, F van Rantwijk, R A Sheldon

文献索引：Appl. Microbiol. Biotechnol. 64(1) , 76-85, (2004)

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摘要

Biocatalytic transformations converting aromatic and arylaliphatic nitriles into the analogous related amide or acid were investigated. These studies included synthesis of the beta-substituted nitrile 3-hydroxy-3-phenylpropionitrile, subsequent enrichment and isolation on this substrate of nitrile-degrading microorganisms from the environment, and a comparative study of enzymatic reactions of nitriles by resting cell cultures and enzymes. Each biocatalyst exhibited a distinctive substrate selectivity profile, generally related to the length of the aliphatic chain of the arylaliphatic nitrile and the position of substituents on the aromatic ring or aliphatic chain. Cell-free nitrilases generally exhibited a narrower substrate range than resting whole cells of Rhodococcus strains. The Rhodococcus strains all exhibited nitrile hydratase activity and converted beta-hydroxy nitriles (but did not demonstrate enantioselectivity on this substrate). The biocatalysts also mediated the synthesis of a range of alpha-hydroxy carboxylic acids or amides from aldehydes in the presence of cyanide. The use of an amidase inhibitor permits halting the nitrile hydratase/amidase reaction at the amide intermediate.