Cation-exchange high-performance liquid chromatography of proteins on poly(aspartic acid)-silica.

A simple cation-exchange material for high-performance liquid chromatography of proteins was developed. Poly(succinimide) reacted rapidly with aminopropyl-silica and the product was hydrolyzed to poly(aspartic acid)-silica. Reaction conditions were optimized to yield a material with an ion-exchange capacity of 430 mg hemoglobin/g material. High-performance liquid chromatographic columns of the material featured excellent performance in terms of capacity, selectivity, recovery of enzyme activity, peak shape and durability. Protein standards and clinical hemoglobin samples were well resolved in minutes. Poly(succinimide)-silica was readily derivatized to give products other than poly(aspartic acid)-silica, and several such materials were prepared. Such materials could be useful for affinity chromatography or enzyme immobilization.