NMR studies of multiple conformations in complexes of Lactobacillus casei dihydrofolate reductase with analogues of pyrimethamine

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00493a022· OSTI ID:5674619

Birdsall, B; Tendler, S J.B.; Feeney, J; Carr, M D ^[1]; Arnold, J R.P.; Thomas, J A; Roberts, G C.K. ^[2]; Griffin, R J; Stevens, M F.G. ^[3]

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1. National Institute for Medical Research, London (United Kingdom)
2. Univ. of Leicester (United Kingdom)
3. Aston Univ., Birmingham (United Kingdom)

{sup 1}H and {sup 19}F NMR signals from bound ligands have been assigned in one- and two-dimensional NMR spectra of complexes of Lactobacillus casei dihydrofolate reductase with various pyrimethamine analogues. The signals were identified mainly by correlating signals from bound and free ligands by using 2D exchange experiments. Analogues with symmetrically substituted phenyl rings give rise to {sup 1}H signals from four nonequivalent aromatic protons, clearly indicating the presence of hindered rotation about the pyrimidine-phenyl bond. Analogues with symmetrically substituted phenyl rings give rise to {sup 1}H signals from four nonequivalent aromatic protons, clearly indicating the presence of hindered rotation about the pyrimidine-phenyl bond. Analogues containing asymmetrically substituted aromatic rings exist as mixtures of two rotational isomers (an enantiomeric pair) because of this hindered rotation and the NMR spectra revealed that both isomers (forms A and B) bind to the enzyme with comparable, though unequal, binding energies. In this case two complete sets of bound proton signals were observed. The relative orientations of the two forms have been determined from NOE through-space connections between protons on the ligand and protein. Ternary complexes with NADP{sup {plus}} were also examined.

• OSTI ID: 5674619
• Journal Information: Biochemistry; (USA), Vol. 29:41; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
OXIDOREDUCTASES
NUCLEAR MAGNETIC RESONANCE
PYRIMIDINES
CHEMICAL SHIFT
FLUORINE 19
LACTOBACILLUS
LIGANDS
NADP
OVERHAUSER EFFECT
PROTONS
AZINES
BACTERIA
BARYONS
COENZYMES
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
FLUORINE ISOTOPES
HADRONS
HETEROCYCLIC COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEI
NUCLEONS
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RESONANCE
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques