Biotransformation acrylonitrile

Both enzymatic and nonenzymatic biotransformation of acrylonitrile occurs. Acrylonitrile is capable of covalently binding to proteins and other macromolecules such as lipids or nucleic acids, or acrylonitrile can also be directly conjugated to glutathione and excreted in urine as cyanoethylmercapturic acid. 

Ghanayem Bl, Ahmed AE. 1982. In vivo biotransformation and biliary excretion of 1-14C-acrylonitrile in rats. Arch Toxicol 50 175-185. 

Gut I, Nerudova J, Kopecky J, et al. 1975. Acrylonitrile biotransformation in rats, mice, and Chinese hamsters as influenced by the route of administration and by phenobarbital, SKF 525-A, cysteine, dimercaprol, or thiosulfate. Arch Toxicol 33 151-161. 

One of the best examples for discussing biotransformations in neat solvents is the enzymatic hydrolysis of acrylonitrile, a solvent, to acrylamide, covered in Chapter 7, Section 7.1.1.1. For several applications of acrylamide, such as polymerization to polyacrylamide, very pure monomer is required, essentially free from anions and metals, which is difficult to obtain through conventional routes. In Hideaki Yamada s group (Kyoto University, Kyoto, Japan), an enzymatic process based on a nitrile hydratase was developed which is currently run on a commercial scale at around 30 000-40 000 tpy with resting cells of third-generation biocatalyst from Rhodococcus rhodochrous J1 (Chapter 7, Figure 7.1). 

Similar data were obtained for 3-cyanopyridine biotransformation into nicotinamide and nicotinic acid (unpublished data). The higher dependence of the nitrile hydratase deactivation process on temperature has already been observed with other substrates, such as in acrylonitrile bioconversion into acrylamide where the nitrile hydratase half-Ufe dropped from 33 h to approximately 7h when the temperature was varied from 4 to 10 °C [37]. 

Acrylamide is unstable and polymerizes easily therefore the process is carried out at a low temperature (5 °C). Although the cells, which are immobilized on polyacrylamide gel, and the contained enzyme are very stable towards acrylonitrile, the starting material has to be fed continuously to the reaction mixture because of inhibition effects at higher concentrations. The biotransformation is started with an... 

Whole-cell MBR have been utilized in a number of biochemical synthesis reactions. An example used industrially, is growth hormone biosynthesis by the bacteria E. coli (Le-goux et al [4.25]). Using the MBR allows the synthesis of this hormone free from pathogens, like those causing the Creutzfeld-Jacob disease, for example. Other industrial examples include the synthesis of homochiral cyanohydrins (Bauer et al. [4.26]), the production of L-aspartic acid [4.16, 4.27], and the biotransformation of acrylonitrile to acrylamide... 

Acrylamide is the first bulk chemical manufactured using an industrial biotransformation. Acrylamide which is produced 200000 t/a is an important industrial chemical that is mainly processed into water-soluble polymers and copolymers, which find applications as flocculants, paper-making aids, thickening agents, surface coatings, and additives for enhanced oil recovery. The chemical manufacture of acrylamide has been established for a long time, it is based on Cu-catalysis. The production of acrylamide using immobilized whole cells of Rhodococcus rhodochrous is a remarkable example of a lyase-catalyzed commercial process. The enzyme responsible for water addition to the double bond of acrylonitrile is nitrile hydratase (Eq. 4-17) ... 

The detoxification of organonitriles via bioprocesses is also expected to become a cheaper process than the present chemical or physical methods [10-12]. Moreover, important industrial achievements based on NHase-catalyzed bioprocesses have been reported, such as the biotransformation of acrylonitrile into acrylamide, of 3-cyanopyridine into nicotinamide, and of adiponitrile into 5[Pg.283]

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