Superiority ofPseudomonas chlororaphis B23 nitrile hydratase as a catalyst for the enzymatic production of acrylamide

Abstract

Summary. In this paper an explanation is given of how Pseudomonas (P.) chlororaphis B23 can accumulate so much acrylamide of such high purity. One reason is that P. ehlororaphis' B 23 exhibits much greater nitrile hydratase activity than amidase activity; the rate of formation of acrylamide through the nitrile hydratase reaction is at least 4000 times higher than its breakdown catalyzed by amidase. Furthermore, acrylonitrile, a powerful nucleophilic reagent, inactivates the active thiol residue of the amidase, whereas nitrile hydratase is not so susceptible to acrylonitrile. Thus acrylamide is produced but not transformed further. In addition, the nitrile hydratase purified from P. chlororaphis B 23 exhibits high resistance to a high concentration of acrylamide. Some other explanations, and the results of evaluation of the P. chlororaphis B 23 enzyme as a catalyst for the production of acrylamide are discussed.

Crystal structure of aldoxime dehydratase and its catalytic mechanism involved in carbon-nitrogen triple-bond synthesis

“…Two of the fruits of our application-oriented nitrile studies are the current industrial production of acrylamide and nicotinamide using the NHase of Rhodococcus rhodochrous J1 (1,9). On the other hand, the NHase of Pseudomonas chlororaphis B23 (22), which was previously used as the previous-generation catalyst for acrylamide manufacture (8,20,23), is now used for the industrial production of 5-cyanovaleramide (24). In this strain, we identified a unique hemoprotein that catalyzes the dehydration of aliphatic aldoximes to the corresponding nitriles (25), naming it aliphatic aldoxime dehydratase (OxdA); it has been approved as a unique enzyme by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB): EC 4.99.1.5 (www.chem.qmul.ac.uk/iubmb/enzyme/EC4/99/1/5.html).…”

Discovery of a reaction intermediate of aliphatic aldoxime dehydratase involving heme as an active center

“…One of the fruits of our applicationoriented nitrile studies is the current industrial production of acrylamide and nicotinamide using the NHase of Rhodococcus rhodochrous J1 (1,9). On the other hand, the NHase of Pseudomonas chlororaphis B23 (22), which was previously used as a catalyst for acrylamide manufacture (8,20,23), is now used for the industrial production of 5-cyanovaleramide (24). Recently, we discovered a novel hemoprotein that catalyzes the dehydration of aliphatic aldoximes to the corresponding nitriles in P. chlororaphis B23 (25) and named it aliphatic aldoxime dehydratase (OxdA); it has been approved as a new enzyme by Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB): EC 4.99.1.5.…”

Interrelations of chemistry and biotechnology-VI. Microbial production of commodity chemicals (Technical Report)

“…In developing this enzymatic reaction, various culture conditions were tested (Yamada, et al, 19861, and the enzyme activity of strains was improved by mutagenesis(Ryun0 et al., 1988). Together, the culture medium and mutation studies significantly improved nitrile hydratase activity (Nagasawa et al, 1989a). With Nitto Chemical Industry, we developed the process for industrial use.…”