NMR studies of binding of 5-FdUDP and dCDP to ribonucleoside-diphosphate reductase from Escherichia coli.
Related Articles NMR studies of binding of 5-FdUDP and dCDP to ribonucleoside-diphosphate reductase from Escherichia coli.
Biochim Biophys Acta. 1995 Mar 15;1247(2):284-92
Authors: Roy B, Decout JL, Béguin C, Fontecave M, Allard P, Kuprin S, Ehrenberg A
5-Fluoro-2'-deoxyuridine-5'-diphosphate (5-FdUDP) has been synthesised using an original route, previously applied to the synthesis of natural nucleoside diphosphates. The interaction between 5-FdUDP and the enzyme ribonucleoside-diphosphate reductase (EC 1.17.4.1) has been studied with 19F-NMR. The product analogue is shown to be in fast exchange with substrate binding sites on protein subunit 1 (R1) of ribonucleoside-diphosphate (NDP) reductase. The number of binding sites is reduced to half when the complete holoenzyme R1R2 is formed. The temperature dependence of the line broadening of 5-FdUDP was studied using 19F-NMR, and of dCDP and dUDP using 1H-NMR. The temperature dependences are complex and a molecular model in which R1 is in a temperature dependent equilibrium between at least two conformations is suggested in order to explain the observed behaviour. Binding of a ligand to the substrate binding sites affects the conformational equilibrium in a ligand specific way. Formation of the holoenzyme R1R2 also affects the equilibrium.
PMID: 7696321 [PubMed - indexed for MEDLINE]
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PubMed