PARTIALLY-HYDROPHOBIZED POLYMER PARTICLES DERIVED FROM N,N-DIMETHYLAMINOPROPYLACRYLAMIDE FOR ENDOTOXIN REMOVAL FROM ACIDIC PROTEIN SOLUTION

Novel copolymeric adsorbents for the selective removal of endotoxin fr om an acidic protein solution were prepared. The adsorbents comprise s pherical copolymers derived from N,N-dimethylaminopropylacrylamide (DM APAA) and divinylbenzene (DVB). When the molar ratio of DMAPAA to DVB was 80/20 (amino-group content: 5.1 meq/g) and the pore size (molecula r mass exclusion of polysaccharide, M(lim)) was 4000 to 10000. DMAPAA/ DVB showed high endotoxin-adsorbing activity at pH 5.0 to 9.0 and ioni c strengths of mu = 0.05 to 0.4. The capacity of the adsorbent (M(lim) : 4000) was 390 mu g of endotoxin (lipopolysaccharide purified from E. coli O111:B4) per ml of the adsorbent using the batchwise method. The apparent dissociation constant be tween endotoxin and the adsorbent w as 2.2 x 10(-12) M. On the other hand, the adsorption of bovine serum albumin, an acidic protein, by the adsorbent increased with an increas e in M(lim) from 4000 to 10000, but decreased with an increase in ioni c strength (mu) from 0.05 to 0.2. As a result, DMAPAA/DVB (80/20) (M(l im): 4000) selectively removed endotoxin from various acidic protein s olutions at pH 7.0 and mu = 0.05. The residual concentration of endoto xin in the protein solution always decreased to a concentration lower than 0.1 ng/ml, and recovery of the protein was more than 97%.