title: 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 alpha-carboxylate of methotrexate was found to prevent interaction of the gamma-carboxylate with the imidazole of His 28. Estimates of the contributions to the binding energy from the alpha-carboxylate-Arg 57 and gamma-carboxylate-His 28 interactions have been made from a combination of inhibition and n.m.r. data.
mesh_terms: D005493:Folic Acid Antagonists; D005971:Glutamates / Q000378:metabolism*; D006639:Histidine / Q000378:metabolism; D007780:Lacticaseibacillus casei / Q000201:enzymology*; D009682:Magnetic Resonance Spectroscopy; D008727:Methotrexate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism*
chemical_list: D005493:Folic Acid Antagonists; D005971:Glutamates; D006639:Histidine; C040894:methotrexate-gamma-monoamide; C040895:methotrexate-alpha-monoamide; D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate