scholarly journals Ethylene production from α-oxo-γ-methylthiobutyric acid is a sensitive measure of ligninolytic activity by Phanerochaete chrysosporium

1982 ◽  
Vol 206 (2) ◽  
pp. 423-425 ◽  
Author(s):  
R L Kelley ◽  
C A Reddy
Keyword(s):  
Hydroxyl Radical ◽  
Phanerochaete Chrysosporium ◽  
Ethylene Production ◽  
Oh Radical ◽  
Nutritional Parameters ◽  
Sensitive Measure ◽  
Ligninolytic Activity

Production of hydroxyl radical in ligninolytic cultures was determined by measuring the alpha-oxo-gamma-methylthiobutyric acid-dependent production of ethylene gas. The results showed that the pattern of ethylene production was very similar to that of ligninolytic activity [[14C]lignin leads to 14CO2). Furthermore, nutritional parameters, which are known to affect ligninolytic activity, affected OH.-radical-dependent ethylene production in a similar fashion. The results indicate that assay for ethylene production from alpha-oxo-gamma-methylthiobutyric acid is a simple and sensitive measure of ligninolytic activity by Phanerochaete chrysosporium.

AbInitio SCF MO calculations on the reaction of hydroxyl radical with cytosine

1986 ◽  
Vol 64 (5) ◽  
pp. 914-919 ◽  
Author(s):  
Beverley G. Eatock ◽  
William L. Waltz ◽  
Paul G. Mezey
Keyword(s):  
Hydroxyl Radical ◽  
Radiation Damage ◽  
Gas Phase ◽  
Solvent Effects ◽  
Oh Radical ◽  
Mo Calculations ◽  
Relative Stabilities ◽  
Ring Atom ◽  
Living Tissues ◽  
Abinitio Calculations

Abinitio calculations have been carried out on the relative stabilities of various possible products of the reaction between cytosine and the OH radical. These products are of importance in modelling radiation damage to living tissues. The preferred theoretical gas-phase addition site is the C6 ring atom according to these calculations. The analysis of a series of possible contributions to solvent effects strongly suggests the predominance of intermolecular H bonds in stabilizing the experimentally observed C5 adduct.

scholarly journals Free hydroxyl radical is not involved in an important reaction of lignin degradation by Phanerochaete chrysosporium Burds

1985 ◽  
Vol 226 (2) ◽  
pp. 455-460 ◽  
Author(s):  
T K Kirk ◽  
M D Mozuch ◽  
M Tien
Keyword(s):  
Hydroxyl Radical ◽  
Phanerochaete Chrysosporium ◽  
Fenton Reaction ◽  
Lignin Degradation ◽  
Mechanism Of Formation ◽  
Mass Spectral ◽  
Free Hydroxyl ◽  
Lignin Model ◽  
Trapping Agent ◽  
Fenton System

Hydroxyl radical (HO.) has been implicated in the degradation of lignin by Phanerochaete chrysosporium. This study assessed the possible involvement of HO. in degradation of lignin substructural models by intact cultures and by an extracellular ligninase isolated from the cultures. Two non-phenolic lignin model compounds [aryl-C(alpha)HOH-C(beta)HR-C(gamma)H2OH, in which R = aryl (beta-1) or R = O-aryl (beta-O-4)] were degraded by cultures, by the purified ligninase, and by Fenton's reagent (H2O2 + Fe2+), which generates HO. The ligninase and the cultures formed similar products, derived via an initial cleavage between C(alpha) and C(beta) (known to be an important biodegradative reaction), indicating that the ligninase is responsible for model degradation in cultures. Products from the Fenton degradation were mainly polar phenolics that exhibited little similarity to those from the biological systems. Mass-spectral analysis, however, revealed traces of the same products in the Fenton reaction as seen in the biological reactions; even so, an 18O2-incorporation study showed that the mechanism of formation differed. E.s.r. spectroscopy with a spin-trapping agent readily detected HO. in the Fenton system, but indicated that no HO. is formed during ligninase catalysis. We conclude, therefore that HO. is not involved in fungal C(alpha)-C(beta) cleavage in the beta-1 and beta-O-4 models and, by extension, in the same reaction in lignin.

scholarly journals Spectrum of the hydroxyl radical

1969 ◽  
Vol 47 (18) ◽  
pp. 1945-1957 ◽  
Author(s):  
C. Carlone ◽  
F. W. Dalby
Keyword(s):  
High Resolution ◽  
Hydroxyl Radical ◽  
Dissociation Energy ◽  
Spin Splitting ◽  
Oh Radical ◽  
Rotational Constants ◽  
Upper Limit ◽  
Vibrational Levels ◽  
State Formula ◽  
Potential Maximum

The B2Σ+ → A2Σ+ and C2Σ+ → A2Σ+ systems of OH and OD were photographed at high resolution. The apparent dissociation energy D0(A2Σ+) is calculated to be (18 847 ± 15) cm−1 for OH and (19 263 ± 15) cm−1 for OD. An upper limit to D0(X2Π3/2) of OH is deduced to be (35 420 ± 15) cm−1. Evidence for a potential maximum in the B2Σ+ state, which is about 100 cm−1 larger than that in the A2Σ+ state, is presented.The broadening of the rotational lines in several bands of both systems has established a strong predissociation of the A2Σ+ state near ν = 5 in OH. The lifetime of these predissociated levels is ≈10−11 s. A definite identification of the predissociating state has not been possible.Newly-discovered vibrational levels in the C2Σ+ state have led to the following constants, in cm−1, of the OH radical in the C2Σ+ state:[Formula: see text]Rotational constants and spin splitting constants in the A2Σ+ and B2Σ+ states, more accurate than previously available, are presented.

scholarly journals Atmospheric chemistry of trans-CF<sub>3</sub>CH=CHF: products and mechanisms of hydroxyl radical and chlorine atom initiated oxidation

2008 ◽  
Vol 8 (1) ◽  
pp. 1069-1088
Author(s):  
M. S. Javadi ◽  
R. Søndergaard ◽  
O. J. Nielsen ◽  
M. D. Hurley ◽  
T. J. Wallington
Keyword(s):  
Environmental Impact ◽  
Hydroxyl Radical ◽  
Partial Pressure ◽  
Chlorine Atom ◽  
Atmospheric Chemistry ◽  
Oh Radical ◽  
Smog Chamber ◽  
O2 Partial Pressure ◽  
Cl Atom

Abstract. Smog chamber/FTIR techniques were used to study the products and mechanisms of OH radical and Cl atom initiated oxidation of trans-CF3CH=CHF in 700 Torr of N2/O2 diluent at 295±1 K. Hydroxyl radical initiated oxidation leads to the formation of CF3CHO and HC(O)F in yields which were indistinguishable from 100% and were not dependent on the O2 partial pressure. Chlorine atom initiated oxidation gives HC(O)F, CF3CHO, CF3C(O)Cl, and CF3C(O)CHFCl. The yields of CF3C(O)Cl and CF3C(O)CHFCl increased at the expense of HC(O)F and CF3CHO as the O2 partial pressure was increased over the range 5–700 Torr. The results are discussed with respect to the atmospheric chemistry and environmental impact of trans-CF3CH=CHF.

The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation

2000 ◽  
Vol 279 (3) ◽  
pp. C868-C875 ◽  
Author(s):  
Suwei Wang ◽  
Stephen S. Leonard ◽  
Jianping Ye ◽  
Min Ding ◽  
Xianglin Shi
Keyword(s):  
Hydroxyl Radical ◽  
A549 Cells ◽  
Sodium Formate ◽  
Binding Activity ◽  
Lung Epithelial Cells ◽  
Oh Radicals ◽  
Oh Radical ◽  
Dna Binding Activity ◽  
P53 Activation ◽  
Radical Generation

The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (·OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O2 −·), hydrogen peroxide (H2O2), and ·OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H2O2 from O2 −· radicals, increased p53 activity. Catalase, an H2O2 scavenger, eliminated ·OH radical generation and inhibited p53 activation. Sodium formate and aspirin, ·OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H2O2. NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased ·OH radical generation, dramatically enhanced p53 activation. Thus ·OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.

The multi-channel reaction of the OH radical with 5-hydroxymethylcytosine: a computational study

RSC Advances ◽  
2016 ◽  
Vol 6 (16) ◽  
pp. 13349-13357 ◽  
Author(s):  
Lingxia Jin ◽  
Caibin Zhao ◽  
Cunfang Liu ◽  
Suotian Min ◽  
Tianlei Zhang ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Hydroxyl Radical ◽  
Computational Study ◽  
Tumor Development ◽  
Oh Radical ◽  
Dna Oxidative Damage

The hydroxyl radical may attack the new cytosine derivative 5-hydroxymethylcytosine (5-hmCyt), causing DNA oxidative damage. Two distinct mechanisms have been explored and our results provide some evidence between 5-hmCyt and tumor development.

Abinitio SCF MO calculations on the reactions of OH radical with pyridine and pyridinium ion

1982 ◽  
Vol 60 (7) ◽  
pp. 813-819 ◽  
Author(s):  
M. C. Anthony ◽  
W. L. Waltz ◽  
P. G. Mezey
Keyword(s):  
Hydroxyl Radical ◽  
Experimental Information ◽  
Electron Delocalization ◽  
Oh Radical ◽  
Reaction Paths ◽  
Mo Calculations ◽  
Relative Stabilities ◽  
Electrophilic Character ◽  
Determining Factor ◽  
Pyridinium Ion

Relative energies of various products formed in the reaction of pyridine and pyridinium ion with the hydroxyl radical are calculated using non-empirical SCF MO techniques. The favourable electron delocalization in the meta-products, rather than the electrophilic character of the OH radical is the determining factor of relative stabilities. Calculated energy barriers along approximate reaction paths correlate with the available experimental information.

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