R. Tyagi et Mn. Gupta, NONCOVALENT AND REVERSIBLE IMMOBILIZATION OF CHEMICALLY-MODIFIED AMYLOGLUCOSIDASE AND BETA-GLUCOSIDASE ON DEAE-CELLULOSE, Process biochemistry, 29(6), 1994, pp. 443-448
The acylation of amino groups of proteins by pyromellitic dianhydride
(PMDA) leads to an increase in negative charges on the protein surface
by 4 units for every amino group modified. This reaction has been use
d to modify enzymes for the purpose of adsorption on DEAE-cellulose. T
he 49% amino groups of amyloglucosidase were modified with 90% residua
l enzyme activity. Whereas the native enzyme bound to DEAE-cellulose a
nd could be eluted out with 0.1 M sodium chloride, the modified enzyme
exhibited stronger binding and could only be eluted with 0.25 M sodiu
m chloride. In the case of adsorbed native enzyme, heating at 60-degre
es-C for 1 h led to desorption of 97% protein. In the case of the modi
fied enzyme, the immobilized preparation retained full enzyme activity
under similar conditions. beta-Glucosidase (which did not bind to DEA
E-cellulose) upon modification with PMDA was found to bind to DEAE-cel
lulose and could be eluted out with 97% protein recovery by washing wi
th O.2 M sodium chloride. Thus, chemical modification with PMDA may be
a useful and general strategy for obtaining enzyme derivatives for re
versible adsorption on anion exchangers.