OH radical reactions with the hydrophilic component of sphingolipids

2021 ◽  
Author(s):  
Alexandra Lisovskaya ◽  
Oleg Shadyro ◽  
Olav Schiemann ◽  
Ian Carmichael
Keyword(s):  
Epr Spectroscopy ◽  
Pulse Radiolysis ◽  
Radical Reactions ◽  
Head Group ◽  
Oh Radical

We probe OH radical interactions with sphingolipid head-group models by EPR spectroscopy and pulse radiolysis.

Radiolysis of Cytosine, 5-Methyl Cytosine and 2'-Deoxycytidine in Deoxygenated Aqueous Solution A Pulse Spectroscopic and Pulse Conductometric Study of the OH Adduct

1978 ◽  
Vol 33 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Alfred Hissung ◽  
Clemens von Sonntag
Keyword(s):  
Pulse Radiolysis ◽  
Radical Reactions ◽  
Oh Radical ◽  
Conductivity Measurements ◽  
Free Radical Reactions ◽  
Product Mixture ◽  
Conductometric Study ◽  
Methyl Cytosine ◽  
G Value ◽  
Induced Reaction

Abstract Using the pulse radiolysis technique the OH adducts of cytosine, 5-methyl cytosine and 2'-deoxycytidine were investigated in alkaline N2O saturated aqueous solutions. Ab-sorption spectra were recorded and their change with time was correlated with the change in conductivity. An OH -induced reaction (1.4·108)·mol-1·s-1) was observed with OH adducts of cytosine and 5-methyl cytosine leading to radicals (pK=10.3), the G-values of which were 3.2 and 1.6 respectively (conductivity measurements). These intermediates were assigned to the C-5 OH radical adducts. After completion of the free radical reactions (2k = 6 · 108)·mol-1·s-1) the resulting product mixture showed pK-values of 8.3 (cytosine, G=0.6), 10.5 (5-methyl cytosine, G=0.8), 10.7 (cytosine, G=1.5; 2′-deoxycytidine, G=1.5) and 12.4 (cytosine, no G-value, determinable with optical detection). Ammonia, which is a product measured after γ-radiolysis of all the three compounds investigated (G(NH3) = 0.6 ± 0.1), is not released within 15 ms after the pulse.

Transient ion pairs from OH-radical reactions: Pulse radiolysis of aqueous alkyl iodide solutions

1973 ◽  
Vol 21 (2) ◽  
pp. 412-414 ◽  
Author(s):  
U. Brühlmann ◽  
H. Büchler ◽  
F. Marchetti ◽  
R.E. Bühler
Keyword(s):  
Pulse Radiolysis ◽  
Ion Pairs ◽  
Radical Reactions ◽  
Alkyl Iodide ◽  
Oh Radical

Submicrosecond studies in pulse radiolysis by time-resolved EPR spectroscopy

1975 ◽  
Vol 35 (4) ◽  
pp. 566-568 ◽  
Author(s):  
A.D. Trifunac ◽  
K.W. Johnson ◽  
B.E. Clifft ◽  
R.H. Lowers
Keyword(s):  
Epr Spectroscopy ◽  
Pulse Radiolysis ◽  
Time Resolved

Mechanism of OH radical reactions with thymine and uracil derivatives

1986 ◽  
Vol 108 (19) ◽  
pp. 5968-5972 ◽  
Author(s):  
Slobodan V. Jovanovic ◽  
Michael G. Simic
Keyword(s):  
Radical Reactions ◽  
Oh Radical ◽  
Uracil Derivatives

Phenylalanine: Its ˙OH and SO4˙⁻-Induced Oxidation and Decarboxylation. A Pulse Radiolysis and Product Analysis Study

1993 ◽  
Vol 48 (6) ◽  
pp. 761-770 ◽  
Author(s):  
Degui Wang ◽  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Side Reactions ◽  
Intramolecular Electron Transfer ◽  
Oh Radical ◽  
Product Analysis ◽  
Water Elimination ◽  
Deprotonation Reaction ◽  
Type Radical ◽  
Radical Yield

Phenylamine has been oxidized by radiolytically generated hydroxyl and sulfate radicals, the ensuing intermediates and their reactions have been studied by pulse radiolysis and product analysis in the absence and presence of oxidants such as Fe(CN)63- and O2. Upon OH radical attack, hydroxycyclohexadienyl-type radicals are mainly formed while Η-abstraction reactions can be neglected. In the presence of Fe(CN)63- these radicals are for the most part oxidized to the corresponding tyrosines (80%), except for the ipso-OH-adduct radicals (≈ 20%). It is concluded that ˙OH-addition is almost random, but with a slight avoidance of the metaposition relative to the ortho-, para- and ipso-positions. Oxygen adds reversibly to the OH-adduct radicals (kf = 1.8 × 108 dm3 mol-1 s-1, kr = 5.4 × 104 s-1). In this case, tyrosine formation occurs by HO2˙-elimination. However, due to side reactions, tyrosine formation only reaches 52% of the OH radical yield. The tyrosine yield drops to 10% in the absence of an oxidant.Upon SO4˙⁻-attack, decarboxylation becomes a major process (33% of SO4˙⁻) alongside the production of tyrosines (43%). Here, with Fe(CN)63- as the oxidant the formation of p-Tyr (18.5%) and m-Tyr (16.5%) is preferred over o-Tyr formation (8.5%). It is believed that in analogy to other systems a radical cation is formed immediately upon SO4˙⁻-attack which either reacts with water under the formation of hydroxycyclohexadienyl-type (“OH-adduct”) radicals, or decarboxylates after intramolecular electron transfer. The radical cation can also arise indirectly through H+-catalysed water elimination from the ˙OH-adduct radicals. At pH 2 and a dose rate of 0.0046 Gy s-1 CO2 formation matches the OH radical yield when ˙OH is the attacking radical. Below pH 2, G(CO2) decreases with falling pH. This indicates the occurrence of another, unimolecular, pathway under these conditions competing effectively with decarboxylation. This appears to be a relatively slow deprotonation reaction of the carboxylprotonated phenylalanine radical cation which gives rise to the benzyl-type radical.

ChemInform Abstract: Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis

ChemInform ◽  
2010 ◽  
Vol 33 (31) ◽  
pp. no-no
Author(s):  
Soumyakanti Adhikari ◽  
Tulsi Mukherjee
Keyword(s):  
Free Radical ◽  
Pulse Radiolysis ◽  
Radical Reactions ◽  
Free Radical Reactions ◽  
Kinetics Of

Mechanism of OH Radical Reactions with HCN and CH3CN:  OH Regeneration in the Presence of O2

2007 ◽  
Vol 111 (23) ◽  
pp. 5086-5091 ◽  
Author(s):  
Annia Galano
Keyword(s):  
Radical Reactions ◽  
Oh Radical

Radical reactions in reverse micelles studied by pulse radiolysis

2020 ◽  
Vol 177 ◽  
pp. 109105
Author(s):  
Jerzy L. Gebicki ◽  
Lidia Gebicka
Keyword(s):  
Reverse Micelles ◽  
Pulse Radiolysis ◽  
Radical Reactions
Sign in / Sign up

Export Citation Format

Share Document