Structural comparison of complexes of methotrexate analogues with Lactobacillus casei dihydrofolate reductase by two-dimensional /sup 1/H NMR at 500 MHz
The authors have used two-dimensional (2D) NMR methods to examine complexes of Lactobacillus casei dihydrofolate reductase and methotrexate (MTX) analogues having structural modifications of the benzoyl ring and also the glutamic acid moiety. Assignments of the /sup 1/H signals in the spectra of the various complexes were made by comparison of their 2D spectra with those complexes containing methotrexate where we have previously assigned resonances from 32 of the 162 amino acid residues. In the complexes formed with the dihalomethotrexate analogues, the glutamic acid and pteridine ring moieties were shown to bind to the enzyme in a manner similar to that found in the methotrexate-enzyme complex. Perturbations in /sup 1/H chemical shifts of protons in Phe-49, Leu-54, and Leu-27 and the methotrexate H7 and NMe protons were observed in the different complexes and were accounted for by changes in orientation of the benzoyl ring in the various complexes. Binding of oxidized or reduced coenzyme to the binary complexes did not result in different shifts for Leu-27, Leu-54, or Leu-19 protons, and thus, the orientation of the benzoyl ring of the methotrexate analogues is not perturbed greatly by the presence of either oxidized or reduced coenzyme. In the complex with the ..gamma..-monoamide analog, the /sup 1/H signals of assigned residues in the protein had almost identical shifts with the corresponding protons in the methotrexate-enzyme complex for all residues except His-28 and, to a lesser extent, Leu-27. This indicates that while the His-28 interaction with the MTX ..gamma..-CO/sub 2//sup -/ is no longer present in this complex with the ..gamma..-amide, there has not been a major change in the overall structure of the two complexes. This behavior contrasts to that of the ..cap alpha..-amide complex where /sup 1/H signals from protons in several amino acid residues are different compared with their values in the complex formed with methotrexate.
- Research Organization:
- National Institute for Medical Research, London (England)
- OSTI ID:
- 5271287
- Journal Information:
- Biochemistry; (United States), Vol. 26:26
- Country of Publication:
- United States
- Language:
- English
Similar Records
Proton nuclear magnetic resonance studies of the effects of ligand binding on ryptophan residues of selectively deuterated dihydrofolate reductase from Lactobacillus casei
Evidence for two interconverting protein isomers in the methotrexate complex of dihydrofolate reductase from Escherichia coli
Related Subjects
METHOTREXATE
NUCLEAR MAGNETIC RESONANCE
OXIDOREDUCTASES
INHIBITION
CHEMICAL SHIFT
COMPLEXES
LACTOBACILLUS
PH VALUE
PROTONS
ANTIMETABOLITES
BACTERIA
BARYONS
DRUGS
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
HADRONS
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEONS
RESONANCE
550601* - Medicine- Unsealed Radionuclides in Diagnostics