Affinity Partition of Enzymes with Dextran-Bound Procion Yellow HE-3G: Effect of Ligand Density

Affinity partition of enzymes has in most cases been carried out in dextran-PEG systems by attaching an affinity ligand to PEG. The ligand is enriched in the upper phase of the two-phase system. The ligand can be bound to the PEG molecule in only two positions, i.e. via the two terminal hydroxyl groups. Many of the works on affinity partition have been done with (mainly) monosubstituted PEG. It is of interest for the practical use of affinity partition for enzyme extraction to know the effects of high densities of ligand. We have therefore studied the effect of the number of ligand molecules per “carrier” polymer molecule (ligand molar ratio) on the affinity partition effect. Dextran has been chosen as ligand carrier because of its high degree of attaching points (hydroxyl groups). As ligand has been used a triazine dye with high affinity for enzymes such as lactate dehydrogenase and 3-phosphoglycerate kinase.