Improvement in Selectivity of Anhydrotrypsin-Immobilized Diol Silica Column by the Use of Eluent Containing Calcium Ion

Abstract The disadvantage of anhydrotrypsin-immobilized diol silica column, retention of basic peptides having no Arg or Lys at their C-termini and no retention of certain C-termina! Arg peptide, was overcome by using 10 mM acetate buffer (pH 6.0) containing 20 mM CaCI2 as an eluent. The role of calcium ion was suggested to be attributable to masking of negatively charged sites which were present intrinsically on the diol silica and produced extrinsically on the support during activation and/or immobilization process.