The 1H-NMR assignments of the aromatic resonances in complexes of Lactobacillus casei dihydrofolate reductase and the origins of their chemical shifts

Stereospecific assignments of the leucine methyl resonances in the 1H NMR spectrum of Lactobacillus casei dihydrofolate reductase

A general method is described for the stereospecific assignment of methyl resonances in protein NMR spectra based on selective deuteration procedures. A selectively deuterated dihydrofolate reductase from L. casei was prepared by incorporating stereoselectively deuterated L-leucine, (2S,4R)[5,5,5-2H3]leucine. By comparing the COSY spectra of the dihydrofolate reductase-methotrexate complexes formed using deuterated and non-deuterated enzyme the stereospecific assignments for resonances of all 13 leucine residues were obtained by noting the absence of cross-peaks in spectra from the deuterated proteins.

NMR studies of interactions of ligands with dihydrofolate reductase

NMR spectroscopy is a useful technique for studying interactions, conformations and dynamic processes within ligand-protein complexes. Several examples of the application of the method to studies of complexes of anti-folate drugs with their target enzyme, dihydrofolate reductase, are discussed.