Industrial Biotransformations

Nitrile hydratase
Rhodococcus rhodochrous
Fig. 4.2.1.84 – 4
EC 4.2.1.84
● As inducer urea is used, which is much cheaper than methacrylamide for the Pseudomonas
chlororaphis. This allows an increase in the amount of L-NHase in the cell free extract to more
than 50 % of the total soluble protein.
● The nitrile hydratases act also on other nitriles with yields of 100 %. The most impressive
example is the conversion of 3-cyanopyridine to nicotinamide. The product concentration is
about 1,465 g · L –1 . This conversion (1.17 g · L –1 dry cell mass) can be named ‘pseudocrystal
enzymation’ since at the start of the reaction the educt is solid and with ongoing reaction it is
solubilized. The same is valid for the product which crystallizes at higher conversions so that
at the end of the reaction the medium is solid again (see also Lonza, page 480).
● The following table shows some examples and the end concentrations of possible products for
Rhodococcus rhodocrous J1 induced by crotonamide:
484