Purification of phenylalanine ammonia-lyase in PEG1000/Na2SO4 aqueous two-phase system by a two-step extraction

The effects of molecular weight and concentration of PEG and various salts on the partitioning of PAL from Rhodotorula glutinis were studied in PEG/salts aqueous two-phase systems at pH 8.8 and 25 °C. With the application of 11.0%PEG1000/14.0%Na2SO4, and 11.0%PEG1000/14.0%Na2SO4/5.3%Na2CO3, purification of PAL by a two-step extraction was proposed in this work. Compared to the conventional salting-out step, 3.7 times of the purification factor (9.3-fold) and a comparable recovery yield (80.6%) were obtained in this method. Therefore, the work offers a useful method for PAL purification and the two-step extraction could replace the conventional salting-out step in the purification.