Interaction of oligopeptides with heparin

Abstract

This heparin affinity chromatography study revealed some very interesting aspects with respect to oligopeptide retention. The first and most surprising effect observed was that oligopeptides with no aromatic groups were not retained on the column while those with aromatic groups were retained. The aromatic interaction was determined to be related to a charge transfer -like interaction as electron donating groups on the aromatic moiety increased retention on the column and electron withdrawing groups on the aromatic moiety deceased retention time. Column retention was dependent on oligopeptide size; the tripeptides were not retained while tetrapeptides and the larger hexapeptides were effectively retained if they contained some aromatic functionality. Retention was pH dependent; low pH's of ∼2.5 were most effective while neutral pH was not effective in retaining the oligopeptides on the heparin affinity column. In addition to the aromatic interaction, retention was dependent on the hydrophobicity of the oligopeptides as well as their ability to hydrogen bond as determined by eluent solvent effects on the heparin affinity column. These results have led us design and carry out other experiments to determine more accurately the type and the degree of oligopeptide to heparin interaction.