INTERACTIONS OF PROTEINS WITH BONDED-PHASE ION-EXCHANGERS

The ion-exchange properties of several commercial bonded-phase supports were studied to determine their applicability for protein separations. Because of the complexity and multiple functionality of protein molecules, UV-absorbing ions with unit charges were used initially to proble ion-exchange properties. The anion exchangers studied showed ambiguous properties, but elution of an organic cation from a pellicular cation exchanger was consistent with ion-exchange theory. With proteins, however, constradictions were found. The elution of reference proteins from the cation exchanger showed that mixed mechanisms occurred. For example, bovine serum albumin and ovalbumin were retained at a pH above teir isoionic points, and their retention times increased rather than decreased with incresing eluent molarity. The mixed mechanisms and the lower diffusivities of protein led to higher heights equivalent to a theoretical plate. Nevertheless, mixtures of reference proteins and protein isolates were resolved. © 1979.