REVERSIBLE IMMOBILIZATION OF CHEMICALLY-MODIFIED TRYPSIN ON DEAE-CELLULOSE

The surface charge on a protein may be changed for binding to ion-exch angers. Trypsin was modified by pyromellitic dianhydride (PMDA) to inc rease its surface negative charges. The trypsin derivative with 29% of the amino groups modified bound (unlike trypsin) to DEAE-cellulose. T he protein could be eluted quantitatively by using 0.25 M NaCl. The pH optimum and K(m) of the enzyme do not show any drastic change on immo bilization. A succinylated derivative of trypsin was also prepared, an d its binding to DEAE-cellulose was compared with the derivative obtai ned after PMDA modification. The approach described in this work provi des a method for reversible immobilization of proteins/enzymes to ion- exchangers. By using this approach it is also possible to control the strength of binding by varying the extent of chemical modification.