Preparation of agarose by fractionation from the spectrum of polysaccharides in agar

Abstract

A logical method for the preparation of agarose was developed based on the knowledge that agar consists of a spectrum of charged polysaccharides. The highly charged polysaccharides were removed by a two-stage washing procedure and agaroses of varying purity were prepared by fractionation of the purified agar. An agarose (0.6% sulfate and 0.05% pyruvic acid) equivalent to commercial agaroses was obtained by a modified polyethylene glycol procedure. Fractionation of the purified agar on DEAE-Sephadex A-50 yielded an agarose with 0.05% sulfate and less than 0.01% pyruvic acid. An essentially neutral agarose with 0.02% sulfate and no detectable pyruvic acid was obtained by fractionation of the polyethylene glycol agarose on DEAE-Sephadex A-50. The distribution, concentration, and type of charged polysaccharides in agars and agaroses may explain the anomalies reported when these preparations are used in various biological techniques. © 1971.