Nalpha-(pteroyltetra (gamma-glutamyl))-lysine as a ligand for the purification of thymidylate synthetase by affinity chromatography.

Nalpha-(pteroyltetra (gamma-glutamyl))-lysine Sepharose was synthesized and shown to be a stable high capacity affinity matrix capable of bringing about the purification of Lactobacillus casei thymidylate synthetase to maximum specific activity from crude extracts in high yield. Under conditions optimal for binding of thymidylate synthetase, dihydrofolate reductase was not bound.