Nitrilase-catalyzed hydrolysis of 3-aminopropionitrile at high concentration with a tandem reaction strategy for shifting the reaction to β-alanine formation

• A nitrilase BjNIT3397 effectively catalyzed the hydrolysis of 3-aminopropionitrile at substrate concentration up to 3 M.
• With the increase of substrate concentration, 3-aminopropanamide was formed.
• A tandem reaction strategy was developed to effectively prevent the formation of 3-aminopropanamide.
• This offers a possibility of producing β-alanine and l-aspartic acid in one process.

Given the importance of β-alanine, the nitrilase BjNIT3397 from Bradyrhizobium japonicum strain USDA110 was examined toward the hydrolysis of 3-aminopropionitrile. It has been found that nitrilase BjNIT3397 effectively hydrolyzed 3-aminopropionitrile with substrate concentration up to 3 M (210 g/L) at the pH 7.3 and temperature 30 °C. With the increase of substrate concentration from 0.6 to 3 M, 3-aminopropanamide was formed and its percentage in the products was increased up to 33%. In order to reduce the formation of 3-aminopropanamide, aspartate ammonia-lyase and fumaric acid were added into the reaction system to consume the byproduct ammonia. As expected, the reaction was shifted toward the formation of β-alanine, resulting in the decrease of 3-aminopropanamide from 33% to 3%. Therefore, a tandem reaction strategy was developed to effectively prevent the formation of 3-aminopropanamide. This might also offer a possibility of producing β-alanine and l-aspartic acid in one process.

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