Partition coefficients of alpha-amylase in aqueous two-phase systems PEG + MgSO4.7H2O + H2O at 298 K

Partition coefficients of alpha-amylase have been determined in a polyethylene glycol (average molecular mass 8000)/MgSO4.7H2O aqueous two-phase system at 298 K and the influence of polymer, salt and initial enzyme concentration on partition was investigated. Correlations are proposed which relates the partition coefficient to the initial enzyme concentration and the concentration difference between phases of polymer and salt. The free volume change, related to the densities of the separate phases, has a direct dependence with such polymer and salt concentration differences, respectively, and is then used to facilitate future estimations. Thus, the partition coefficient is a function of this physical parameter and the initial enzyme concentration employed (1.25, 2.50 and 5.00 g dm-3).