A 1H n.m.r. study of the role of the glutamate moiety in the binding of methotrexate to Lactobacillus casei dihydrofolate reductase

Abstract

The binding of a series of amide derivatives of methotrexate to Lactobacillus casei dihydrofolate reductase has been studied by inhibition constant measurements and by 1H n.m.r. spectroscopy. Amide modification of the α‐carboxylate of methotrexate was found to prevent interaction of the γ‐carboxylate with the imidazole of His 28. Estimates of the contributions to the binding energy from the α‐carboxylate‐Arg 57 and γ‐carboxylate‐His 28 interactions have been made from a combination of inhibition and n.m.r. data. 1984 British Pharmacological Society