Aqueous two-phase system (polyethylene glycol plus ionic liquid) for extraction of alpha-amylase: phase diagrams, systems characterization and partition study

摘要

The increasing demand for safe and effective methods for the separation of biological materials combining the advantageous properties of polyethylene glycol (PEG) (1500 g mol(-1)or 4000 g mol(-1)) and ionic liquid has led to attractive and promising applications of the new aqueous biphasic systems. In this work, the liquid-liquid extraction process with aqueous two-phase systems (ATPS) was studied for alpha-amylase partitioning. The phase diagrams composed of PEG (1500 or 4000) g mol(-1) + 1-ethyl-3-methylimidazolium chloride + water, were determined experimentally by the turbidimetric method at different temperatures T = (293.15, 303.15, 313.15 and 323.15) K. The effect of temperature and polymer molar mass on the phase diagrams, as well as the phase densities, refractive indexes and electrical conductivity were evaluated. Subsequently, the alpha-amylase partitioning was performed, where the partition coefficient was determined, besides the activity and selectivity. It was found that a temperature decrease and a polymer molar mass increase favored the formation of two phases. It was also found that alpha-amylase showed a preference for the bottom phase composed of PEG and the systems composed of PEG 1500 presented better results.