A pI of 4.8 means the protein will have a net NEGATIVE charge at pH
values of above 4.8. The problems you have with DEAE may result from
strong binding of the protein to the resin. You may have to elute the
DEAE column with higher NaCl concentrations. For some help, look up some
purification procedures for other acidic proteins, such as calmodulin.
--
Bruce G. Allen Ph.D.
Research Assistant Professor
Montreal Heart Institute
5000, East Belanger St.
Montreal (Quebec) H1T 1C8
Tel: 514-376-3330 ext. 3591
Fax: 514-376 1355
