Interaction of methotrexate, folates, and pyridine nucleotides with dihydrofolate reductase: calorimetric and spectroscopic binding studies.
AUTOR(ES)
Subramanian, S
RESUMO
The thermodynamic parameters, deltaG, deltaH, and deltaS characterizing the tight binding of methotrexate, folates, and pyridine nucleotides to chicken liver dihydrofolate reductase (5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) have been determined from calorimetric and fluorescence measurements. At 25 degrees the binding of NADPH and NADP+ is characterized by small negative enthalpies and large positive entropies whereas the binding of the folates and methotrexate is accompanied by large negative enthalpies and small negative entropies. In addition, the enthalpy of methotrexate-enzyme interaction demonstrates a proton transfer associated with binding; this is not the case with folate and dihydrofolate, thus confirming the conclusions drawn from the observed difference spectra characteristic of the interaction of methotrexate and substrates with the enzyme. The implications of these results are discussed in terms of the nature of the binding process, conformational changes in the enzyme, and the nature of the active site region.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=392742Documentos Relacionados
- Conformational Changes Induced in Dihydrofolate Reductase by Folates, Pyridine Nucleotide Coenzymes, and Methotrexate*
- Interaction of dihydrofolate reductase with methotrexate: Ensemble and single-molecule kinetics
- Alpha-pyridine nucleotides as substrates for a plasmid-specified dihydrofolate reductase.
- Refolding of Escherichia coli dihydrofolate reductase: sequential formation of substrate binding sites.
- Methotrexate, pneumonitis, and infection.
