PVA-chitosan based immobilization of NHase for dynamic kinetic resolution of rac-mandelonitrile

A recently published paper by Pawar and Yadav in Industrial and Engineering Chemistry Research entitled “Enantioselective Enzymatic Hydrolysis ofrac-Mandelonitrile to R-Mandelamide by Nitrile Hydratase Immobilized onPoly(vinyl alcohol)/Chitosan–Glutaraldehyde Support” describes the improvement in performance the nitrile hydratase from Rhodococcus rhodocrous ATCC BAA-870 exhibits when immobilized on PVA/chitosan. The reaction being tested is the DKR of rac-mandelonitrile.

Supporting a nitrile hydratase for better performance

There is a new accepted manuscript for the Journal of Molecular Catalysis B: Enzymatic which adds to the literature on the support of a nitrile hydratase to increase this notoriously sensitive enzyme’s robustness.  PVA/Chitosan-glutaraldehyde cross-linkednitrile hydratase as reusable biocatalyst for conversion of nitriles to amides by SV Pawar and GD Yadav  describes how to prepare a cross linked assembly containing the NHase from Rhodococcus rhodochrous ATCC BAA-870. When they test this immobilized enzyme in the hydration of 3-cyanopyridine, they find it is able to withstand a higher temperature and more basic conditions. They also show that their preparation is a reusable format which retains 50% of activity after 8 batches.

The figure below from the paper shows relative activity of free and immobilized NHase over time at 45 degrees C in 0.1M phosphate buffer. The upper line is the immobilized form.