R. Tyagi et al., REVERSIBLE IMMOBILIZATION OF CHEMICALLY-MODIFIED TRYPSIN ON DEAE-CELLULOSE, Biotechnology and applied biochemistry, 20, 1994, pp. 93-99
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.