Evaluation of the use of volatile electrolyte system produced by ammonia and carbon dioxide in water for the salting-out of proteins: Precipitation of porcine trypsin

In this work, the precipitation of porcine trypsin in solutions of volatile electrolytes formed by ammonia and carbon dioxide was investigated. The solubility curve of trypsin at 4 °C was determined by measuring the compositions of the precipitate and supernatant phases. Analysis showed that ammonium carbamate is able to induce trypsin salting-out. The verified salting-out property of ammonium carbamate, the easy removal of the salt out of the protein precipitate and mother-solution and the high activity recovery demonstrate the feasibility of using ammonium carbamate as precipitant agent.