Helmholtz Gemeinschaft

Search
Browse
Statistics
Feeds

EPR stopped-flow studies of the reaction of the tyrosyl radical of protein R2 from ribonucleotide reductase with hydroxyurea

Item Type:Article
Title:EPR stopped-flow studies of the reaction of the tyrosyl radical of protein R2 from ribonucleotide reductase with hydroxyurea
Creators Name:Lassmann, G. and Thelander, L. and Graeslund, A.
Abstract:The reaction of the functional tyrosyl radical in protein R2 of ribonucleotide reductase from E. coli and mouse with the enzyme inhibitor hydroxyurea has been studied by EPR stopped-flow techniques at room temperature. The rate of disappearance of the tyrosyl radical in E. coli protein R2 is k2 = 0.43 M-1 s-1 at 25 degrees C. The reaction follows pseudo-first-order kinetics up to 450 mM hydroxyurea indicating that no saturation by hydroxyurea takes place even at this high concentration. Transient nitroxide-like radicals from hydroxyurea have been detected for the first time in the reaction of hydroxyurea with protein R2 from E. coli and mouse, indicating that 1-electron transfer from hydroxyurea to the tyrosyl radical is the dominating mechanism in the inhibitor reaction. The hydroxyurea radicals appear in low steady-state concentrations during 2-3 half-decay times of the tyrosyl radical and disappear thereafter.
Keywords:Electron Spin Resonance Spectroscopy, Escherichia Coli, Free Radicals, Hydroxyurea, Kinetics, Macromolecular Substances, Oxidation-Reduction, Ribonucleotide Reductases, Animals, Mice
Source:Biochemical and Biophysical Research Communications
ISSN:0006-291X
Publisher:Academic Press (U.S.A.)
Volume:188
Number:2
Page Range:879-887
Date:30 October 1992
Official Publication:https://doi.org/10.1016/0006-291X(92)91138-G
PubMed:View item in PubMed

Repository Staff Only: item control page

Open Access
MDC Library