Selective Removal Of Dna From Bioproducts By Polycation-Immobilized Cellulose Beads

This paper describes a method for the selective removal of DNA from various cellular products using columns packed with polycation-immobilized cellulose beads. Polyethyleneimine (PEI), poly-N,N-dimethylaminopropylacrylamide (poly(DAPA)) and poly(epsilon-lysine) (P epsilon L), all of which have cationic properties, were used as the ligands on the beads. Cellufine-GC15((R)) and -CPC (R) were used as cellulose matrices. Adsorption of DNA by the beads was determined using a batchwise method or a column method. Each bead type showed high DNA adsorbing activity at pH 7.0 and ionic strengths of mu = 0.05 - 0.8. The larger the pore size of the beads, the larger the DNA-adsorbing activity. The DNA adsorbing capacities per wet mL of PEI-, poly(DAPA)- and P epsilon L immobilized Cellufine-CPC with large pore sizes, were 3.7, 3.2, and 1.8 mg, respectively. When a protein, such as bovine serum albumin (BSA) or gamma-globulin, was present in solution with the DNA under physiological conditions (pH 7.0, mu = 0.2), the DNA selectivity of the PEI immobilized Cellufine-CPC columns was unsatisfactory, because both the DNA and the protein were adsorbed into the column. In contrast, the poly( DAPA) immobilized Cellufine-CPC column selectively removed DNA from each protein solution contaminated with DNA under similar conditions: the DNA concentration in each treated protein solution was below 10 ng mL(-1), and high recovery of each protein (> 92%) was obtained.