The alkoxy radical, RCH2Ȯ, as a free radical product in x-irradiated single crystals of nucleosides and nucleotides

1977 ◽  
Vol 67 (3) ◽  
pp. 1211 ◽  
Author(s):  
William A. Bernhard ◽  
David M. Close ◽  
Jürgen Hüttermann ◽  
Herbert Zehner
Keyword(s):  
Free Radical ◽  
Single Crystals ◽  
Alkoxy Radical ◽  
Radical Product ◽  
Free Radical Product

Metabolic Activation of Carbon Tetrachloride to a Free-Radical Product: Studies using a Spin Trap

1978 ◽  
Vol 6 (5) ◽  
pp. 962-964 ◽  
Author(s):  
A. INGALL ◽  
K. A. K. LOTT ◽  
T. F. SLATER ◽  
S. FINCH ◽  
A. STIER
Keyword(s):  
Free Radical ◽  
Carbon Tetrachloride ◽  
Spin Trap ◽  
Metabolic Activation ◽  
Radical Product ◽  
Free Radical Product

Radical reactions of nitric oxide synthases

2004 ◽  
Vol 71 ◽  
pp. 39-49 ◽  
Author(s):  
Dennis J. Stuehr ◽  
Chin-Chuan Wei ◽  
Jerome Santolini ◽  
Zhi- Qiang Wang ◽  
Mika Aoyagi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Electron Transfer ◽  
Free Radical ◽  
Structural Features ◽  
Nitric Oxide Synthases ◽  
Radical Reactions ◽  
Radical Product ◽  
O2 Activation ◽  
Health And Disease ◽  
Free Radical Product

NOSs (nitric oxide synthases) are flavohaem enzymes that function broadly in human health and disease. We are combining mutagenesis, crystallographic and rapid kinetic methods to understand their mechanism and regulation. The NOSs create a transient tetrahydrobiopterin radical within the enzyme to generate their free radical product (NO). Recent work is revealing how critically important this process is at all levels of catalysis. This article will synthesize four seemingly disparate but related aspects of NOS tetrahydrobiopterin radical formation: (i) how it enables productive O2 activation by providing an electron to the enzyme haem, (ii) what structural features help to regulate this electron transfer, (iii) how it enables NOS to synthesize NO from its diamagnetic substrate and (iv) how it allows NOS to release NO after each catalytic cycle instead of other nitorgen oxide-containing products.

FREE RADICAL PRODUCT FORMED BY THE REACTION OF DEHYDROASCORBIC ACID WITH AMINO ACIDS

1974 ◽  
Vol 3 (2) ◽  
pp. 125-128 ◽  
Author(s):  
Mitsuo Namiki ◽  
Midori Yano ◽  
Tateki Hayashi
Keyword(s):  
Amino Acids ◽  
Free Radical ◽  
Dehydroascorbic Acid ◽  
Radical Product ◽  
Free Radical Product

scholarly journals A method for obtaining linear reciprocal plots with caeruloplasmin and its application in a study of the kinetic parameters of caeruloplasmin substrates

1972 ◽  
Vol 129 (2) ◽  
pp. 273-283 ◽  
Author(s):  
S. N. Young ◽  
G. Curzon
Keyword(s):  
Free Radical ◽  
Free Radical Oxidation ◽  
Side Chain ◽  
Small Range ◽  
Radical Product ◽  
Radical Oxidation ◽  
Rate Limiting Step ◽  
Straight Line ◽  
Rate Limiting ◽  
Ylacetic Acid

1. The curved plots of 1/v against 1/[S] obtained when caeruloplasmin oxidizes NN-dimethyl-p-phenylenediamine were investigated. The first free-radical oxidation product of caeruloplasmin oxidation of NN-dimethyl-p-phenylenediamine is required for curvature, as straight-line plots were obtained when activities were measured either before appreciable free-radical product had appeared or in the presence of ascorbate, which reduced it back to NN-dimethyl-p-phenylenediamine. 2. In the presence of ascorbate linear reciprocal-plots were obtained with all of the 37 substrates tested. Vmax. values varied over only an eightfold range and those for the 20 p-amino compounds over only a twofold range. Km values, however, varied over a 104-fold range. The small range of Vmax. values indicates that the rate-limiting step in caeruloplasmin action is relatively independent of the nature of the substrate. Km values suggest that substrates bind primarily by ring electrons, although certain side-chain groups increased the Km in a manner unrelated to likely changes of ring-electron densities. A mechanism involving repulsion between negative charges on the substrate and the enzyme was supported by the variation of the Km of 5-hydroxyindol-3-ylacetic acid with pH.

An ESR Study of Light- and Temperature-Induced Free Radical Conversions in Single Crystals of Dihydrouracil

1979 ◽  
Vol 77 (1) ◽  
pp. 62 ◽  
Author(s):  
I. Egtvedt ◽  
E. Sagstuen ◽  
T. Henriksen
Keyword(s):  
Free Radical ◽  
Single Crystals
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