Abstract:In this study, the methods to prepare metallothionein (MT) from the fermentation of yeast (Pichia pastoris) using high temperature heating and isoelectric precipitation were compared and used ias a pre-treatment process to remove the miscellaneous proteins in the fermentation broth. Next, the ultrafiltration membrane, DEAD-FF chromatography, and the action of EDTA chelation were conducted to get high content of MT product from the yeast fermentation. The antioxidant activity in vitro of obtained MT was also evaluated. The results indicated that the high temperature heating (80 ℃ heating 10 min, then centrifugation at 8000 r/min for 20 min) showed better effects on the removal of heteroprotein and retention of MT, compared with the treatment of isoelectric precipitation. Additionally, the MT was significantly extracted and purified from the fermentation broth by the following processes of ultrafiltration concentration (50 ku) and DEAE-FF chromatography. The combined Cu2+ by extracted MT were removed by the chelation of EDTA, the concentrations of which were decreased by 61.90%. Finally, the obtained MT exhibited the re-adsorption capacity of metal elements and good capacities of OH·, O2-·, and DPPH scavenging activity. These results can provide a reference and theoretical basis for the extration, the development, and the application of MT from yeast resources.
