Aqueous Two Phase Extraction of Lectin from Pisum Sativum Seeds

Abstract

The diversified properties of the lectins from different sources and their applications in biotechnological and pharmaceutical industries demand the economically feasible and scalable purification strategy. Pisum sativum seed lectin (Psl) has specific properties like anti-HIV reverse transcriptase, anti-HCV, anti-cancer, and mitogenic activities. The chromatographic process, which was commercially applied for the purification of this lectin, has number of limitations to implement in industrial scale. The Aqueous two phase extraction (ATPE) technique, a modified liquid-liquid extraction, was adopted for the recovery and partial purification of Psl from its seed crude extract. The PEG 6000- trisodium citrate system (ATPS) was identified as a suitable system by analyzing the influence of type of citrate salt, PEG molecular weight, phase components concentration, pH, additive (NaCl) and phase volume ratio on the partitioning behavior of Psl from the aqueous solution of pure Psl. The maximum partitioning coefficient of 14.5 was obtained for 18% PEG 6000-16% trisodium citrate system with 1% NaCl at pH of 8 and volume ratio of 1.32. Further, the optimized condition for the selective partitioning of Psl to the top phase from the crude extract of Pisum sativum seed was achieved in the ATPS formed with PEG 6000-sodium citrate at 41.01% TLL, 2% NaCl at pH of 7.5 with crude load of 20% and volume ratio of 0.76. The optimum value of crucial variables (PEG and salt concentration, NaCl, and pH) and their individual and interactive impact on the recovery and purity was identified using Response surface methodology. The optimum process conditions for different goals of extraction and purification were obtained by employing the desirability-based optimization tool and were validated experimentally. The feasibility of continuous operation of the extraction process has also been demonstrated in the Rotating disc contactor. Modeling of the equilibrium characteristics and the partitioning of the Psl was attempted using Artificial neural network.