Extraction of protease from bilimbi (Averrhoa bilimbi L.) / Nur ‘Ain Mohamad Kharoe

Protease was extracted from bilimbi {Averrhoa bilimbi L.) and the juice obtained was purified by using two different concentrations of ammonium sulfate solution (40 and 60% (w/v)). The proteases were analysed for pH stability, temperature stability, storage stability, SDS-PAGE (molecular weight distribution), protein concentration and protein content. Protein content of bilimbi is 0.89 g. Protease activity at both ripening stage and 40 and 60% ammonium sulfate purification was optimum at pH 2 to 4 and at temperature 30 to 50°C. As for storage stability at 4 °C, the protease activity decreased with storage time. Molecular weight distribution indicated that the proteases protein bands fall between 10 to 220 kDa with protein band at 50 kDa seen in both unripe and ripe bilimbi proteases purified with 40%) ammonium sulfate. As the concentration of ammonium sulfate decreases, the protein concentration increase at both ripening stages. Purification using 40%> ammonium sulfate precipitation could be a successful method to purify proteases from bilimbi especially from the unripe stage.