in order to identify the most suitable aqueous two phase system. The results in terms of recovery and purity in both top (PEG rich) and bottom (salt rich) phases are presented in Table 1. Among the salts, the highest enzyme activity recovery (84.7%) with 3.78 fold purification was observed in case of magnesium sulphate (Table 1) compared to other salts studied. The partition coefficients of invertase and total protein are shown in Fig. 1. It can be observed (from the table and figure) that the target protein preferentially partitioned to the bottom phase, implying a strong preference of invertase