THE REMOVAL OF ENDOTOXINS FROM PROTEIN SOLUTIONS USING COLUMN PACKINGS WITH AMINATED POLY(GAMMA-METHYL L-GLUTAMATE) SPHERES

A method is described for the selective removal of endotoxins from various protein solutions using columns packed with aminated poly(gamma-methyl L-glutamate) (PMLG-NH2) spheres. The PMLG-NH2 adsorbents showed a high adsorbing activity for endotoxins which had an ionic strength of mu = 0.05-1.0 and pH 5.0-9.0. The endotoxin-adsorbing capacity per millilitre of the wet adsorbent increased from 0.40 to 1.35 mg (E. coli O111: B4 LPS) at mu = 0.2 and pH 7.0 while the amino-group content of the adsorbent increased from 0.8 to 3.5 meg g(-1). The PMLG-NH2-3.5 has an amino-group content of 3.5 meq g(-1). This column packing selectively adsorbed endotoxins, without loss of the protein, from a gamma-globulin or cytochrome c solution which contained endotoxins at mu = 0.05 and pH 7.0. On the other hand, when bovine serum albumin (BSA) was present in solution with endotoxins, both the endotoxins and the BSA were adsorbed by the column. The BSA-adsorbing activity increased with increasing amino-group content of the adsorbent. However, this undesirable adsorption was suppressed with increasing ionic strength of the buffer. As a result, when the pa which had an amino-group content of 1.5 meq g(-1) was used in conditions of mu= 0.2 and pH 7.0, the endotoxins were removed from a BSA-containing solution without affecting the recovery of the BA.