Difference between two strong cation-exchange resins, namely sulfonium
type and sulfate type regarding both their salt tolerance and
hydrophobicity were investigated. There is only tiny variation between
sulfate and sulfonic group and at the first glance it seems unlikely
that it could be the reason for changed selectivity and salt tolerance
that was detected in our preliminary experiments. For that reason salt
tolerance and hydrophobicity of both ligands was investigated by using
two representative polymethacrylate-based ion exchangers as for the
sulfonium type TOYOPEARL GigaCap S-650M and for the sulfate type
TOYOPEARL Sulfate-650F. In addition some in-silico calculations were
performed for model substances representing the sulfonium and sulfate
group, and significant differences were calculated regarding their
hydrophobicity. These experiments confirmed the working hypothesis that
salt tolerance and higher affinity and selectivity for some human plasma
derived vitamin K dependent clotting factors and inhibitors are
interrelated and dependent from the presence of the sulfate group. The
affinity for these proteins was experimentally verified by separation of
clotting factor IX from the prothrombin complex concentrate. Presented
results show that a simple and fast separation between clotting factor
IX and other vitamin K dependent clotting factors II, VII and X is
possible, only if the resin with the sulfate, and not with sulfonic acid
ligand was applied. Consequently, an immediate application of undiluted
feedstock or the eluate from previous isolation step to sulfate resin is
possible, and a significant optimization of downstream process can be
achieved.