Influence of immobilization on enzyme activity in aqueous-organic cosolvent mixtures

Four enzymes viz. polyphenol oxidase, trypsin, acid phosphatase and peroxidase were adsorbed on eudragit-S100, chitin and chitosan. The enzyme activities of bath free as well as immobilized enzymes were assayed in the presence of varying concentrations of some organic cosolvents viz. acetonitrile, tetrahydrofuran, dimethyl formamide and dioxane. In many cases, the enhanced activity observed in the presence of low concentration of organic cosolvent (upto 20%) were greater in the case of immobilized enzymes. In some cases, immobilization led to greater retention of enzyme activity in the presence of higher concentrations of an organic cosolvent. It was found that influence of the matrix upon co-solvent tolerance varies with the solvent but did not correlate with a solvent parameter such as log P. It is shown that adsorption is a good approach while preparing immobilized enzymes for working in media where concentrations of organic cosolvents do not exceed about 20%.