Calculation of Standard Reduction Potentials of Amino Acid Radicals and the Effects of Water and Incorporation into Peptides

2017 ◽  
Vol 122 (1) ◽  
pp. 439-445 ◽  
Author(s):  
David M. Close ◽  
Peter Wardman
Keyword(s):  
Amino Acid ◽  
Reduction Potentials ◽  
Amino Acid Radicals

Assessing the Effect of Ligand Proximity on Chiroptical and Other Properties in Cobalt(III) Model, Tyrosine-Like Complexes

1995 ◽  
Vol 60 (12) ◽  
pp. 2097-2106 ◽  
Author(s):  
František Jursík ◽  
Ronald D. Archer
Keyword(s):  
Amino Acid ◽  
Inductive Effect ◽  
Lewis Acidity ◽  
Side Chain ◽  
Ground State Structure ◽  
Amino Acid Side Chain ◽  
State Structure ◽  
Reduction Potentials ◽  
Alkyl Groups ◽  
C Nmr

A series of new cobalt(III) octahedral complexes of the general formula Na[Co(ohb-aa)2] (ohb-aa = N-(o-hydroxybenzyl)amino acid anion); amino acid = glycine, (S)-α-alanine, α-aminoisobutyric acid, (S)-valine, (S)-norvaline and (S)-leucine) were prepared by the charcoal catalyzed reaction of the appropriate ligand with [Co(NH3)6]3+ in alkaline aqueous solution. Complexes obtained have, regardless of the amino acid used, the same facial all-trans symmetry (CoN2O4 chromophore) with the vicinal effects as the entire source of the optical activity. 13C NMR spectra reveal that the leucine derivative has, due to the steric reasons, a different ground state structure. Absorption maxima reflect a positive inductive effect from the amino acid side chain carbon atoms. Complexes of the ligands bearing electrophobic alkyl groups exhibit more negative E1/2 in comparison with the glycine derivative, reduction of which occurs at a more positive potential. Reduction potentials do not correlate with cobalt(III) Lewis acidity modulated by ligands.

Repair of Amino Acid Radicals of Apolipoprotein B100 of Low-Density Lipoproteins by Flavonoids. A Pulse Radiolysis Study with Quercetin and Rutin†

Biochemistry ◽  
2002 ◽  
Vol 41 (36) ◽  
pp. 11057-11064 ◽  
Author(s):  
Paulo Filipe ◽  
Patrice Morlière ◽  
Larry K. Patterson ◽  
Gordon L. Hug ◽  
Jean-Claude Mazière ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pulse Radiolysis ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Apolipoprotein B100 ◽  
Amino Acid Radicals

ChemInform Abstract: Nitrate Esters in the Generation of Amino Acid Radicals.

ChemInform ◽  
2010 ◽  
Vol 28 (27) ◽  
pp. no-no
Author(s):  
C. J. EASTON ◽  
A. J. IVORY ◽  
C. A. SMITH
Keyword(s):  
Amino Acid ◽  
Nitrate Esters ◽  
Amino Acid Radicals

scholarly journals Proton-coupled electron transfer: the mechanistic underpinning for radical transport and catalysis in biology

2006 ◽  
Vol 361 (1472) ◽  
pp. 1351-1364 ◽  
Author(s):  
Steven Y Reece ◽  
Justin M Hodgkiss ◽  
JoAnne Stubbe ◽  
Daniel G Nocera
Keyword(s):  
Electron Transfer ◽  
Amino Acid ◽  
Active Sites ◽  
Bond Activation ◽  
Mechanical Effect ◽  
Model Systems ◽  
Tyrosyl Radical ◽  
Quantum Mechanical Effect ◽  
Proton Coupled Electron Transfer ◽  
Amino Acid Radicals

Charge transport and catalysis in enzymes often rely on amino acid radicals as intermediates. The generation and transport of these radicals are synonymous with proton-coupled electron transfer (PCET), which intrinsically is a quantum mechanical effect as both the electron and proton tunnel. The caveat to PCET is that proton transfer (PT) is fundamentally limited to short distances relative to electron transfer (ET). This predicament is resolved in biology by the evolution of enzymes to control PT and ET coordinates on highly different length scales. In doing so, the enzyme imparts exquisite thermodynamic and kinetic controls over radical transport and radical-based catalysis at cofactor active sites. This discussion will present model systems containing orthogonal ET and PT pathways, thereby allowing the proton and electron tunnelling events to be disentangled. Against this mechanistic backdrop, PCET catalysis of oxygen–oxygen bond activation by mono-oxygenases is captured at biomimetic porphyrin redox platforms. The discussion concludes with the case study of radical-based quantum catalysis in a natural biological enzyme, class I Escherichia coli ribonucleotide reductase. Studies are presented that show the enzyme utilizes both collinear and orthogonal PCET to transport charge from an assembled diiron-tyrosyl radical cofactor to the active site over 35 Å away via an amino acid radical-hopping pathway spanning two protein subunits.

Hydrogen transfer in the presence of amino acid radicals

1997 ◽  
Vol 97 (1-4) ◽  
pp. 289-300 ◽  
Author(s):  
Per E. M. Siegbahn ◽  
Margareta R. A. Blomberg ◽  
Robert H. Crabtree
Keyword(s):  
Amino Acid ◽  
Hydrogen Transfer ◽  
Amino Acid Radicals

Nitrate esters in the generation of amino acid radicals

1997 ◽  
pp. 503-508 ◽  
Author(s):  
Christopher J. Easton ◽  
Andrew J. Ivory ◽  
Craig A. Smith
Keyword(s):  
Amino Acid ◽  
Nitrate Esters ◽  
Amino Acid Radicals
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