Effect of several factors on the process of protein solution ultrafiltration

: Ultrafiltration of protein solutions was investigated, using deoxyribonuclease of Actinomyces streptomycini filtered through a membrane based on vinylpyrrolidone-methyl methacrylate copolymers. It was shown that ionization of the protein molecule, level of the applied pressure as well as the protein concentration in the initial solution influenced particle adsorption on the surface and in pores of the molecule and the formation of gel layer reducing the rate of the solution filtration. The following parameters were found to favor the process: pH=7.5 (the value corresponds to the highest stability of the enzyme and the presence of the total negative discharge on the surface of the protein molecule). DNase concentration not more than 2 mg/ml, pressure 2 atm. The retaining capacity of the membrane was 85% and DNAase losses were 20%.