Beneficial effect of hydrotropes on partitioning behaviour of proteins in aqueous two phase systems

Proteins have been partitioned in poly(ethylene glycol) (PEG)-salt systems containing hydrotropes. Hydrotropes are surface active compounds with strong ionic nature with a smaller hydrophobic part as compared to surfactants. The effect of pH, hydrotrope concentration, polymer molecular weight and protein molecular weight on partitioning of proteins including enzymes and their separation has been investigated. The effects of hydrotropes may be explained on the basis of interaction of PEG and the hydrotropes. This is substantiated by measuring the concentration of hydrotropes in both the phases. The practical utilization of the described effect is to enhance the separation of a mixture of proteins by many folds. Preliminary experiments have shown that hydrotropes at low concentrations do not affect enzyme activity and do not have any bactericidal activity.