DEVELOPMENT OF ION-EXCHANGE CRYOGEL FOR PROTEIN PURIFICATION FROM ORA-PRO-NOBIS (Pereskia aculeata Miller) LEAVES

The leaves of ora-pro-nobis (Pereskia aculeata Miller, OPN) present a non-toxic mucilage composed of Arabinogalactan type I associated with proteins, becoming a promising hydrocolloid source for the food industry, however, techniques are needed to purify this biocompound with high purity and yield, reducing the number of downstream steps. Thus, the work aimed to develop ion-exchange cryogels for the purification of proteins from OPN leaf extract obtained by cold extraction in a ratio of 1:2.5 (w/v, leaf/water). Polyacrylamide cryogels were produced by cryo-polymerization (-14 °C/24 hours), dried (60 °C/48 hours), and functionalized using ammonium sulfate (2.75 mol L-1, at pH 9.5) containing the ligands of ion exchange (taurine, cysteine, polyethyleneimine or glutamic acid) at 35 ºC for 20 hours. The adsorption assays of proteins from OPN extract in sodium phosphate buffer (0.25 mol L-1, pH 2.5, 5.5, and 8.5), at 1:1 dilution ratio, were conducted in batch at 25 ºC for 24 h. The cryogel activation method using the glutamic acid as ion exchange ligand was optimized using a Central Composite Rotational Design (CCRD) 22, containing 4 central and 4 axial points, varying the temperature (29 ºC to 71 ºC) and time (17 h to 39 h) of functionalization. Cryogels were characterized in terms of their chemical, morphological, thermal, and mechanical properties. The cryogel functionalized with glutamic acid (cryogel-GA) at 50 ºC/28 hours obtained the best adsorption capacity at pH 5.5 (q = 103.369 ± 4.602 mg g-1), presenting interconnected pores ranging from 6–75 μm, swelling capacity of 14.113 ± 0.867 g g-1 and degree of expansion of 1.569 ± 0.058, in addition to good thermal and mechanical resistance, showing no significant differences in relation to pure cryogels. The results show that cryogel-GA is a promising matrix for use in OPN protein capture processes by ion exchange.