In the precipitation seperation of protein with compressed pressure CO2, the protein stability is a key factor. To test its stability, alkaline proteinase (Subtilisin, from Bacillus licheniformis 2709#) was chosen as a model protein in this process and the proteinase activity and hydrolysis were investigated in detail. In this precipitation process, the ethanol was used as a precipitation assistant in aqueous solution of crude alkaline proteinase. The effects of some operating parameters, including CO2 pres...