Separation of Human Lysozyme from Fermentation Broth of Pichia pastoris by Aqueous Two-Phase Extraction

A new simple procedure using aqueous two-phase system was established for the separation of human lysozyme(HLZ) from the fermentation broth of Pichia pastoris.Effects of the relative molecular mass,concentration of polyethyleneglycol(PEG),Na_2SO_4 and NaCl,and pH value on the partition coefficient of HLZ,the volume ratio of total protein and phase,the yield and the purification factor were studied.Human lysozyme is recovered with a high yield in the top phase when PEG 4000,Na_2SO_4 and NaCl were in the two-phase system with the mass fraction of 0.08,0.13,0.06 respectively at pH 5.6.The purity of HLZ increases by the fractor of 6.5 with a yield of 96.63%.