Immobilisation and characterisation of glucose dehydrogenase immobilised on ReSyn: a proprietary polyethylenimine support matrix

Abstract

Immobilisation of enzymes is of considerable interest due to the advantages over soluble enzymes, including improved stability and recovery. Glucose Dehydrogenase (GDH) is an important biocatalytic enzyme due to is ability to recycle the biological co-factor NAD(P)H)1 using the inexpensive substrate glucose. The ability to recycle co-factors is of importance due to the various biocatalytic applications of co-factor utilising enzymes2. These co-factors are expensive and not readily recoverable from biocatalytic systems. The adoption of a co-factor recycling system comprising of a cofactor regenerating enzyme has to an extent alleviated this drawback by greatly reducing the quantity of co-factor required. This work outlines the optimisation of ReSyn™ for protein binding and enzyme activity maintenance, with subsequent characterisation of the immobilised enzyme, GDH. The highest enzyme activity maintenance achieved for GDH was 42.3%, but varied greatly based on the degree of crosslinking of the polymer network. Lower degrees of crosslinking demonstrated lower enzyme activity maintenance. This was inversely proportional to the quantity of enzyme loading that could be achieved with higher loading being achieved with less polymer crosslinking. The immobilisation further broadened the pH range of the enzyme, particularly in the acidic pH range.