Nitrilase and Nitrile Hydratase

DiCosimo, R. (2007) Nitrilases and nitrile hydratases, in Biocatalysis in the Pharmaceutical and Biotechnology Industries (ed. R.N. Patel), CRC Press LLC, Boca Raton, FL, Chapter 1. 

Nitrilase and Nitrile Hydratase Knowledgebase Jubilant Biosys 165 http //www.jubilantbiosys.com/... 

The nitrile group is a versatile building block, in particular since it can be converted into acids or amides. It undergoes hydrolysis but requires relatively harsh reaction conditions. Nature provides two enzymatic pathways for the hydrolysis of nitriles. The nitrilases convert nitriles directly into acids, while the nitrile hy-dratases release amides. These amides can then be hydrolysed by amidases (see also above). Often nitrile hydratases are combined with amidases in one host and a nitrile hydratase plus amidase activity can therefore be mistaken as the activity of a nitrilase (Scheme 6.32). A large variety of different nitrilases and nitrile hydratases are available [100, 101] and both types of enzyme have been used in industry [34, 38, 94]. 

Nitrilase- and Nitrile Hydratase-Catalyzed Synthetic Processes.377... 

NITRILASE- AND NITRILE HYDRATASE-CATALYZED SYNTHETIC PROCESSES... 

I 75 Nitrilase- and Nitrile Hydratase-catalyzed Enantiosekctive Preparation Table 15.5 Synthesis of enantioenriched y-amino acids... 

Nitrilases and nitrile hydratases are distinct enzymes, apparently differing both with respect to prosthetic groups and reaction mechanisms. 

Microorganisms appear to have evolved separate metabolic pathways for the hydrolysis of inorganic cyanide. Thus most nitrilases and nitrile hydratases investigated so far do not display activity towards cyanide. However recently, as a first exception to this, a nitrilase has been reported that hydrolyses potassium cyanide as well as organic nitriles[29, 301. 

Compilation of the biotransformation information has led to the postulation that the cloned Pseudomonas gene has both nitrilase and nitrile hydratase activities. This novel nitrile hydrolyzing activity is summarized in Figure 8. 

Brady, D., Beeton, A., Zeevart, J., Kgaje, C., van Rantwijk, F., and Sheldon, R.A. (2004) Characterisation of nitrilase and nitrile hydratase biocatalytic systems. Appl. Microbiol. Biotechnol., 64, 76-85. 

Selective nitrile hydrolysis (to acids and amides) Nitrilases and nitrile hydratases... 

High enantioselectivity has been more often described with amidases and nitrileforming enzymes than with the directly nitrile-converting nitrilases and nitrile hydratases. This might indicate a lower stereoselective capacity of directly nitrile-converting enzymes but is probably also in part due to the fact that the stereospecificity of these enzymes has only been the subject of intense study in the last decade. 

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