Enhanced catalytic efficiency of nitrilase from Acidovorax facilis 72W and application in bioconversion of 3-cyanopyridine to nicotinic acid

In this study, the catalytic efficiency using NitA from Acidovorax facilis 72W for nicotinic acid (NA) production was investigated and further improved by site-directed mutagenesis. Results showed that the specific activity of mutated NitA-C2 (F168V-S192F) towards 3-cyanopyridine increased 5-fold to 35Umg−1 protein. Further characterization of the biochemical properties of both nitrilases showed the optimal pH and temperature were 6.0-8.0 and 60°C, respectively, whereas the pH and thermal stability of NitA-C2 were decreased. Finally, whole cell catalysis was adopted for NA production and a 100% conversion yield was achieved under 0.1molL−1 3-cyanopyridine for both strains. Besides, the conversion rate by E. coli BL21 (DE3-pET-nitA-C2) reached to 1.0mmolmin−1 g−1 wet cell weight, which was 3-fold higher than that by E. coli BL21 (DE3-pET-nitA). These results indicated that the mutated NitA-C2 was a promising candidate which holds potential application in biological NA production. Graphical abstract
Source: Journal of Molecular Catalysis B: Enzymatic - Category: Biochemistry Source Type: research