Chemical Fixation of Enzymes to Cyanogen Halide Activated Polysaccharide Carriers

Abstract

Water‐insolubel chymotrypsin, trypsin and papain have been synthesized by covalent fixation of the enzymes to beads of cross‐linked dextran (Sephadex ® ), beads of agarose, and cellulose powder. The fixation procedure involves two simple steps: (a) activation of the polysaccharide polymer by a cyanogen halide; (b) coupling of the protein to the activated polymer in slighly alkaline medium. The activation process can be controlled so as to retain certain useful or essential properties of the carrier material, such as particle shape and swelling capacity. The enzyme conjugates of Sephadex and agarose are therefore especialy suitable for use in the column format. The coupling process is so mild that a large portion of the inherent enzymic activity is conserved. However, the steric properties and other features of the carrier framework often prevents full manifestatuion of the fixed activity. Catalysts that are highly efficient toward small substrates are easily obtainable. Teh agarose‐bound enzymes can even exhibit high activities toward large proteins. Conjugates of the latter type should therefore be particularly useful for the digestion of prtoeins.