English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Escherichia coli class Ia ribonucleotide reductase (RNR) converts ribonucleotides to deoxynucleotides. A diferric-tyrosyl radical (Y 122 •) in one subunit (β2) generates a transient thiyl radical in another subunit (α2) via long-range radical transport (RT) through aromatic amino acid residues (Y 122 ⇆ [W 48 ] ⇆ Y 356 in β2 to Y 731 ⇆ Y 730 ⇆ C 439 in α2). Equilibration of Y 356 •, Y 731 •, and Y 730 • was recently observed using site specifically incorporated unnatural tyrosine analogs; however, equilibration between Y 122 • and Y 356 • has not been detected. Our recent report of Y 356 • formation in a kinetically and chemically competent fashion in the reaction of β2 containing 2,3,5-trifluorotyrosine at Y 122 (F 3 Y 122 •-β2) with α2, CDP (substrate), and ATP (effector) has now afforded the opportunity to investigate equilibration of F 3 Y 122 • and Y 356 •. Incubation of F 3 Y 122 •-β2, Y 731 F-α2 (or Y 730 F-α2), CDP, and ATP at different temperatures (2-37 °C) provides ΔE°'(F 3 Y 122 •-Y 356 •) of 20 ± 10 mV at 25 °C. The pH dependence of the F 3 Y 122 • ⇆ Y 356 • interconversion (pH 6.8-8.0) reveals that the proton from Y 356 is in rapid exchange with solvent, in contrast to the proton from Y 122 . Insertion of 3,5-difluorotyrosine (F 2 Y) at Y 356 and rapid freeze-quench EPR analysis of its reaction with Y 731 F-α2, CDP, and ATP at pH 8.2 and 25 °C shows F 2 Y 356 • generation by the native Y 122 •. F n Y-RNRs (n = 2 and 3) together provide a model for the thermodynamic landscape of the RT pathway in which the reaction between Y 122 and C 439 is ∼200 meV uphill.

journal of the american chemical society

A &gt;200 meV Uphill Thermodynamic Landscape for Radical Transport in <i>Escherichia coli</i> Ribonucleotide Reductase Determined Using Fluorotyrosine-Substituted Enzymes

A >200 meV Uphill Thermodynamic Landscape for Radical Transport in Escherichia coli Ribonucleotide Reductase Determined Using Fluorotyrosine-Substituted Enzymes