Extraction of protease from ora-pro-nobis (Pereskia aculeata Miller) and partial purification in polyethylene glycol plus sodium phosphate aqueous two-phase system

This article studies the influence of pH and extraction solution, time, and solid/liquid ratio on the extraction of protease from ora-pro-nobis. Aqueous two-phase systems (ATPS) formed by polyethylene glycol 1,500 or 4,000 and phosphate were investigated as a purification step for these proteases. The best results were with sodium phosphate pH 7.0, 60 min of extraction, and at the liquid/solid ratio of 21 ml.g(-1). ATPS formed by polyethylene glycol and phosphate were obtained. The increase in molar mass resulted in the expansion of the biphasic region, exclusion volume, and the free volume of the upper phase. The proteases were preferentially partitioned to the upper phase. The free energy indicates that the partition of proteases to the upper phase is a spontaneous process. High selectivity, activity recovery, and the purification factor indicate that the studied systems can be used as a good alternative for the purification of this enzyme. Practical applications An alternative plant protease source obtained from ora-pro-nobis leaves has been investigated for the first time. The results show that experimental conditions established in this work allow the efficient extraction and partial purification of protease.