title: Theoretical study of ribonucleotide reductase mechanism-based inhibition by 2'-azido-2'-deoxyribonucleoside 5'-diphosphates.
abstract: 2'-azido-2'-deoxyribonucleoside 5'-diphosphates are mechanism-based inhibitors of Ribonucleotide Reductase. Considerable effort has been made to elucidate their mechanism of inhibition, which is still controversial and not fully understood. Previous studies have detected the formation of a radical intermediate when the inhibitors interact with the enzyme, and several authors have proposed possible structures for this radical. We have conducted a theoretical study of the possible reactions involved, which allowed us to identify the structure of the new radical among the several proposals. A new reactional path is also proposed that is the most kinetically favored to yield this radical and ultimately inactivate the enzyme. The energetic involved in this mechanism, both for radical formation and radical decay, as well as the calculated Hyperfine Coupling Constants for the radical intermediate, are in agreement with the correspondent experimental values. This mechanistic alternative is fully coherent with remaining experimental data.
authors.affiliation: REQUIMTE/Departamento de Química, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Pereira
authors.forename: Pedro Alexandrino
authors.initials: PA
authors.lastname: Fernandes
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Ramos
mesh_terms: D003853:Deoxyribonucleosides / Q000737:chemistry* / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003853:Deoxyribonucleosides; D004791:Enzyme Inhibitors; D012264:Ribonucleotide Reductases