Isolation of a Aspergillus niger lipase from a solid culture medium with aqueous two-phase systems.

The aim of this work is to find the best conditions to isolate lipase from a solid culture medium of Aspergillus niger NRRL3 strains using aqueous two-phase systems formed with polyethylene glycol and potassium phosphate or polyethylene glycol and sodium citrate. We studied the partitioning of a commercial lyophilizate from A. niger.

Pepsin extraction from bovine stomach using aqueous two-phase systems: molecular mechanism and influence of homogenate mass and phase volume ratio.

Pepsin partitioning, a gastric acid protease, in aqueous two-phase systems of polyethyleneglycol/potassium phosphate, sodium citrate and ammonium sulphate was assayed using polyethylenglycol of different molecular mass. Pepsin was found to be partitioned towards the polymer-rich phase in all the systems, which suggests an important protein-polymer interaction due to the highly hydrophobic character of the protein surface exposed to the solvent. The pepsin partitioning behavior was explained according to Timasheff's preferential interaction theory.