A MNDO SCF-MO theoretical study of the mechanism of [1,2] migrations in free radicals as a model for coenzyme B12 mediated rearrangement reactions

1983 ◽  
pp. 625 ◽  
Author(s):  
James J. Russell ◽  
Henry S. Rzepa ◽  
David A. Widdowson
Keyword(s):  
Free Radicals ◽  
Theoretical Study ◽  
Coenzyme B12 ◽  
Rearrangement Reactions

Site reactivity in the free radicals induced damage to leucine residues: a theoretical study

2015 ◽  
Vol 17 (7) ◽  
pp. 4970-4976 ◽  
Author(s):  
M. E. Medina ◽  
A. Galano ◽  
J. R. Alvarez-Idaboy
Keyword(s):  
Free Radicals ◽  
Theoretical Study ◽  
Kinetically Controlled ◽  
Hydrophobic Media

The reactions of leucine with free radicals are kinetically controlled and are faster in hydrophilic than in hydrophobic media.

Stabilization of the adenosyl radical in coenzyme B12 – a theoretical study

2004 ◽  
Vol 386 (1-3) ◽  
pp. 174-178 ◽  
Author(s):  
Nicole Dölker ◽  
Feliu Maseras ◽  
Per E.M. Siegbahn
Keyword(s):  
Theoretical Study ◽  
Coenzyme B12

scholarly journals Theoretical Study about the Effect of Halogen Substitution on the Reactivity of Antitumor 3-Formylchromones and Their Free Radicals

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Maximiliano Martínez-Cifuentes ◽  
Boris Weiss-López ◽  
Ramiro Araya-Maturana
Keyword(s):  
Free Radicals ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Theoretical Study ◽  
Computational Study ◽  
Bond Dissociation Enthalpy ◽  
Radical Species ◽  
Anticancer Compounds ◽  
Dissociation Enthalpy ◽  
Polarizable Continuum

The mandatory presence of a chlorine atom on the aromatic ring of 6-hydroxy-3-formyl angular chromones, on the respiration inhibition of mammary carcinoma mouse, is explained through a computational study of these compounds. This study analyzes the reactivity of the neutral molecules and their free radicals, in gas phase and with water solvation, incorporated by the polarizable continuum medium (PCM) approach. Electrophilic reactivities were evaluated using Fukui (f+) and Parr (P+) functions. The stabilities of radical species formed by the abstraction of a hydrogen atom from the O-H bond were evaluated by bond dissociation enthalpy (BDE) and spin density (SD) calculations. This study has potential implications for the design of chromone analogues as anticancer compounds.

scholarly journals A Theoretical Study of Chemical Reactivity of Tartrazine Through DFT Reactivity Descriptors

2017 ◽  
Vol 58 (4) ◽  
Author(s):  
Luis Humberto Mendoza Huizar
Keyword(s):  
Free Radicals ◽  
Theoretical Study ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Initial Attack ◽  
Reactivity Descriptors ◽  
Pcm Model ◽  
Total Energies ◽  
Global And Local ◽  
Global Reactivity Descriptors

<p>In this work we have calculated global and local DFT reactivity descriptors for tartrazine at B3LYP/6-311++G (2d,2p) level. Global reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, and total energies were calculated to evaluate the tartrazine reactivity in aqueous and gas conditions. Local reactivity was evaluated through the Fukui function. The influence of the solvent was taken into account with the PCM model. The results indicate that the solvation process modifies the reactivity descriptors values. From our results, it was found that an electrophilic attack allows a direct cleavage of the N=N bond. If a nucleophilic attack is considered as initial attack, it is necessary a second attack by free radicals or electrophiles to cleave the N=N bond. In the case of an initial attack by free radicals, tartrazine requires a subsequent nucleophilic attack to cleave the N=N bond.</p>

Rearrangement Reactions of the Transient Lewis Acids (CF3)3B and (CF3)3BCF2:  An Experimental and Theoretical Study

2004 ◽  
Vol 43 (2) ◽  
pp. 490-505 ◽  
Author(s):  
Maik Finze ◽  
Eduard Bernhardt ◽  
Manfred Zähres ◽  
Helge Willner
Keyword(s):  
Lewis Acids ◽  
Theoretical Study ◽  
Rearrangement Reactions

Theoretical study on the mechanism for the thermal rearrangement reactions of 2-silylethyl acetate H3SiCH2CH2OCOCH3

2009 ◽  
Vol 109 (2) ◽  
pp. 342-348
Author(s):  
Zhongfeng Jia ◽  
Shengyu Feng ◽  
Enfeng Song ◽  
Wenyan Sun ◽  
Lixiao Cong
Keyword(s):  
Theoretical Study ◽  
Thermal Rearrangement ◽  
Rearrangement Reactions

New Free Radicals to Measure Antiradical Capacity: A Theoretical Study

2014 ◽  
Vol 118 (34) ◽  
pp. 10092-10100 ◽  
Author(s):  
Jorge Rafael León-Carmona ◽  
Ana Martínez ◽  
Annia Galano
Keyword(s):  
Free Radicals ◽  
Theoretical Study

Insights into the mechanisms of adenosylcobalamin (coenzyme B12)-dependent enzymes from rapid chemical quench experiments

2009 ◽  
Vol 37 (2) ◽  
pp. 336-342 ◽  
Author(s):  
E. Neil G. Marsh
Keyword(s):  
Free Radicals ◽  
Steady State ◽  
Kinetic Isotope Effect ◽  
Hydrogen Transfer ◽  
Coenzyme B12 ◽  
Hydrogen Atoms ◽  
Glutamate Mutase ◽  
Kinetic Isotope ◽  
Steady State Kinetic ◽  
State Kinetic

Glutamate mutase is one of a group of adenosylcobalamin-dependent enzymes that use free radicals to catalyse unusual and chemically difficult rearrangements involving 1,2-migrations of hydrogen atoms. A key mechanistic feature of these enzymes is the transfer of the migrating hydrogen atom between substrate, coenzyme and product. The present review summarizes recent experiments from my laboratory that have used rapid chemical quench techniques to identify intermediates in the reaction and probe the mechanism of hydrogen transfer through a variety of pre-steady-state kinetic isotope effect measurements.

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