Ion-exchange separation of proteins by polyallylamine-grafted cellulose gel

A cellulose-based anion exchanger bearing water-soluble polycation was tested for separation of proteins. The exchanger was obtained by partial oxidation of cellulose gel by aq. NaIO4 followed by Schiff base formation with polyallylamine (PAA, molecular mass 5000). The retention behavior of proteins for three grades of PAA-cellulose gels, with amino group contents of 0.35, 0.59 and 0.96 mmol/g cellulose, was examined at several pH values and compared with that for conventional DEAE-cellulose gel with amino group content of 1.07 mmol/g cellulose. The retention of proteins by PAA-cellulose gels was remarkably greater than that for the DEAE-cellulose gel. Pairs of proteins having close isoelectric points and molecular masses (human and bovine serum albumins; beta-lactoglobulin A and B) could be separated by the PAA-cellulose gel columns. Such efficiency can be ascribed to high local density of grafted polyallylamine, in contrast to the random and sparse charge distribution in DEAE-cellulose.