the effects of ph upon the c-2 resonances of the 5 histidine residues of escherichia coli mb 1428 dihydrofolate reductase in binary complexes with methotrexate , aminopterin , folate , methopterin , and trimethoprim were studied by 300-mhz 1h nmr spectroscopy .
C0025677
methotrexate
C0002583
aminopterin