scholarly journals Structural characterization of the products of hydroxyl-radical damage to leucine and their detection on proteins

1997 ◽  
Vol 324 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Shan-Lin FU ◽  
Roger T. DEAN
Keyword(s):  
Hydroxyl Radical ◽  
Protein Oxidation ◽  
Degradation Products ◽  
Cellular Systems ◽  
Oxidation Products ◽  
Radical Attack ◽  
Radical Damage ◽  
Nabh4 Reduction

We have previously reported the formation of valine hydroperoxides and aldehydes from hydroxyl-radical attack on free valine and protein molecules. We have also demonstrated that the major degradation products of valine hydroperoxides by several biochemical and cellular systems are the corresponding hydroxides, and therefore proposed that hydroxyvalines may serve as useful in vivo markers for studying protein oxidation. Here we have undertaken the structural elucidation of the oxidation products of leucine, another amino acid which is very susceptible to peroxidation. Hydroxyl-radical (HO•) attack on l-leucine in the presence of oxygen, followed by NaBH4 reduction, gave rise to five major oxidation products which have been isolated and identified. On the basis of chemical and spectroscopic evidence, the five products have been identified as (2S)-γ-hydroxyleucine, (2S,4S)-δ-hydroxyleucine, (2S,4R)-δ-hydroxyleucine, (2S,4R)-4-methylproline (trans-4-methyl-l-proline) and (2S,4S)-4-methylproline (cis-4-methyl-l-proline). The three hydroxyleucines have been confirmed to be the reduction products of the corresponding hydroperoxyleucines, while the two proline analogues are from reduction of their corresponding cyclic Schiff bases. By HPLC analysis using post-column o-phthaldialdehyde derivatization, we have detected hydroxyleucines in the hydrolysates of tripeptides and proteins which had been γ-radiolysed and treated with NaBH4. Furthermore, we demonstrate the occurrence of the hydroxyleucines on proteins in physiological and pathological samples. Hydroxyleucines, like hydroxyvalines, may provide usefulin vivo markers for studying protein oxidation. In the present study we also investigated the competition between leucine, valine and phenylalanine for HO•, and proposed a possible radical-transfer process in such free-radical reactions.

scholarly journals Evidence for roles of radicals in protein oxidation in advanced human atherosclerotic plaque

1998 ◽  
Vol 333 (3) ◽  
pp. 519-525 ◽  
Author(s):  
Shanlin FU ◽  
Michael J. DAVIES ◽  
Roland STOCKER ◽  
Roger T. DEAN
Keyword(s):  
Hydroxyl Radical ◽  
Protein Modification ◽  
Indirect Evidence ◽  
Transition Metal Ions ◽  
Oxidation Products ◽  
Reaction Pathways ◽  
Radical Attack ◽  
Radical Damage ◽  
Human Carotid

Oxidative damage might be important in atherogenesis. Oxidized lipids are present at significant concentrations in advanced human plaque, although tissue antioxidants are mostly present at normal concentrations. Indirect evidence of protein modification (notably derivatization of lysine) or oxidation has been obtained by immunochemical methods; the specificities of these antibodies are unclear. Here we present chemical determinations of six protein-bound oxidation products: dopa, o-tyrosine, m-tyrosine, dityrosine, hydroxyleucine and hydroxyvaline, some of which reflect particularly oxy-radical-mediated reaction pathways, which seem to involve mainly the participation of transition- metal ions. We compared the relative abundance of these oxidation products in normal intima, and in human carotid plaque samples with that observed after radiolytically generated hydroxyl radical attack on BSA in vitro. The close similarities in relative abundances in the latter two circumstances indicate that hydroxyl radical damage might occur in plaque. The relatively higher level of dityrosine in plaque than that observed after radiolysis suggests the additional involvement of HOCl-mediated reactions in advanced plaque.

scholarly journals In Vivo Characterization of the Toxicological Properties of DPhP, One of the Main Degradation Products of Aryl Phosphate Esters

2020 ◽  
Vol 128 (12) ◽  
pp. 127006
Author(s):  
Samia Selmi-Ruby ◽  
Jesús Marín-Sáez ◽  
Aurélie Fildier ◽  
Audrey Buleté ◽  
Myriam Abdallah ◽  
...  
Keyword(s):  
Degradation Products ◽  
Phosphate Esters ◽  
In Vivo Characterization

Glycoxidation, and protein and DNA oxidation in patients with diabetes mellitus

1998 ◽  
Vol 95 (3) ◽  
pp. 331-337 ◽  
Author(s):  
K. KRAPFENBAUER ◽  
R. BIRNBACHER ◽  
H. VIERHAPPER ◽  
K. HERKNER ◽  
D. KAMPEL ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Diabetes Mellitus ◽  
Hydroxyl Radical ◽  
Protein Oxidation ◽  
Type Ii Diabetes ◽  
Dna Oxidation ◽  
Type I ◽  
Type Ii ◽  
Patients With Diabetes ◽  
Radical Attack

1.The role of oxidative stress in the pathogenesis of the diabetic state is being investigated extensively. Although oxidative stress has been reported in terms of glycoxidation, protein oxidation and DNA oxidation in diabetes mellitus, oxidation parameters have not been determined in parallel on the same study population. 2.We studied 24 patients with diabetes mellitus (14 patients with Type I diabetes with a mean age of 62.3±6.3 years and 10 patients with Type II diabetes aged 67.3±5.9 years) and compared them with age-matched non-diabetic controls. Urinary o-tyrosine, 8-hydroxy-2′-deoxyguanosine and pentosidine measurements by HPLC were made on two occasions (t1 and t2). 3.A clear statistical difference was found between diabetic patients and controls at t1 or t2 for 8-hydroxy-2′-deoxyguanosine and pentosidine, but not for o-tyrosine. No significant correlations were found between clinical and other laboratory parameters except high-density lipoprotein and uric acid. We revealed significantly increased glycoxidation and DNA oxidation in patients with Type I and Type II diabetes, but protein oxidation was not different from controls. 4.The finding of increased glycoxidation reflects increased oxidation of the carbohydrate moiety, whereas the increased levels of oxidized DNA may also be interpreted as due to increased DNA repair. The increased 8-hydroxy-2′-deoxyguanosine does not indicate the generation of an individual active oxygen species, but DNA could have been oxidized simply by alkenals from lipid peroxidation, as e.g. malondialdehyde. As no difference in protein oxidation (i.e. o-tyrosine) between diabetics and controls could be revealed, the oxidation of DNA by hydroxyl radical attack is unlikely, as o-tyrosine was proposed as a marker for hydroxyl radical attack. Therefore, the message is that increased glycoxidation can be confirmed, protein oxidation does not appear to take place and increased DNA oxidation is still not proven, as increased 8-hydroxy-2′-deoxyguanosine may simply reflect repair.

scholarly journals Degradation state of organic matter in surface sediments from the Beaufort Shelf: a lipid approach

2012 ◽  
Vol 9 (3) ◽  
pp. 3881-3916 ◽  
Author(s):  
J.-F. Rontani ◽  
B. Charriere ◽  
M. Petit ◽  
F. Vaultier ◽  
H. J. Heipieper ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Surface Sediments ◽  
Degradation Products ◽  
Monounsaturated Fatty Acids ◽  
Protective Role ◽  
Oxidation Products ◽  
Higher Plant ◽  
Abiotic Degradation ◽  
Oxidative Processes

Abstract. The lipid content of surface sediments collected on the Beaufort Shelf was examined. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells) in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxyacids and unusually very high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxyacids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo), while cis/trans isomerization was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the important role played by abiotic oxidative processes in the degradation of marine bacteria and do not support the generally expected refractory character of terrigenous material deposited in deltaic systems.

Characterization of insulin degradation products generated in liver endosomes: In vivo and in vitro studies

1990 ◽  
Vol 72 (3) ◽  
pp. 175-185 ◽  
Author(s):  
Jean-Pierre Clot ◽  
Michel Janicot ◽  
Françoise Fouque ◽  
Bernard Desbuquois ◽  
Pierre-Yves Haumont ◽  
...  
Keyword(s):  
Degradation Products ◽  
In Vitro Studies ◽  
Insulin Degradation

scholarly journals Catecholamine Oxidative Products, but Not Melanin, Are Produced by Cryptococcus neoformans during Neuropathogenesis in Mice

1999 ◽  
Vol 67 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Lide Liu ◽  
Kazumasa Wakamatsu ◽  
Shosuke Ito ◽  
Peter R. Williamson
Keyword(s):  
Cryptococcus Neoformans ◽  
Virulence Factor ◽  
Degradation Products ◽  
Hydriodic Acid ◽  
Oxidation Products ◽  
Oxidative Products ◽  
Specific Degradation ◽  
Catecholamine Oxidation

ABSTRACT Melanin has been proposed as a virulence factor inCryptococcus neoformans, but its presence has not been shown unambiguously in vivo. Validated methods used previously to show production of cryptococcal eumelanin pigment in vitro (P. R. Williamson, K. Wakamatsu, and S. Ito, J. Bacteriol. 180:1570–1572, 1998) were used to assess for production of laccase-derived products in mouse brain of the Lacc+ strains, 2E-TUC, H99 (serotype A), and ATCC 34873 (serotype D), and the Lacc− strain, 2E-TU. Pyrrole-2,3,5-tricarboxylic and pyrrole-2,3-dicarboxylic acid, specific degradation products of catecholamine derivatives such as melanin, were found in all Lacc+ strains, but not in the Lacc− strain, 2E-TU. However, the presence of melanin pigment itself could not be demonstrated in the same cells. Lack of the specific degradation products aminohydroxyphenylalanine and aminohydroxyphenylethylamine in Lacc+ strains upon hydriodic acid hydrolysis showed that pheomelanin was also not produced by the fungus in vivo. These are the first data to support the generation of catecholamine oxidation products by C. neoformans in vivo, but they do not support postenzymatic polymerization of these products to form typical eumelanin, as previously proposed.

scholarly journals Biological fate of amino acid, peptide and protein hydroperoxides

1995 ◽  
Vol 311 (3) ◽  
pp. 821-827 ◽  
Author(s):  
S Fu ◽  
S Gebicki ◽  
W Jessup ◽  
J M Gebicki ◽  
R T Dean
Keyword(s):  
Amino Acid ◽  
Protein Oxidation ◽  
Degradation Products ◽  
Amino Acid Residues ◽  
Biological Degradation ◽  
Amino Acid Peptide ◽  
Biological Fate ◽  
Sodium Borohydride Reduction ◽  
Suitable Marker

In the course of searching for a suitable marker for studying protein oxidation, we have successfully elucidated the structures of three valine hydroperoxides, i.e. beta-hydroperoxyvaline, (2S,3S)-gamma-hydroperoxyvaline and (2S,3R)-gamma-hydroperoxyvaline, which are novel products of protein oxidation. The corresponding valine hydroxides were obtained by sodium borohydride reduction [Fu, Hick, Sheil and Dean (1995) Free Rad. Biol. Med. 19, 281-292]. We hypothesized that valine hydroxides might be the major biological degradation products of valine hydroperoxides and, as such, could be useful markers for the study of protein oxidation in vivo. The aim of this study was to investigate the fate of valine hydroperoxide in selected biological systems by the use of chemiluminescence detection of hydroperoxides and HPLC analysis of O-phthaldialdehyde derivatives of amino acid residues. The degradation of hydroperoxides present on gamma-radiolysed solutions of valine, Pro-Val-Gly, or BSA occurred in the presence of: (1) transition metals (Fe2+, Fe3+, or Cu2+), (2) the detoxifying enzyme GSH peroxidase, (3) human plasma, and (4) J774 mouse monocyte macrophage cells. The major degradation product of valine hydroperoxide recovered in each case was found to be a valine hydroxide. These results suggest that valine hydroxide (derived from the hydroperoxide) may well be a useful in vivo marker for studying protein damage under oxidative stress.

Steady State Radiolysis of Aqueous Aerated Solutions of 5,6-Dihydrothymine. Identification of the Major Degradation Products

1980 ◽  
Vol 35 (12) ◽  
pp. 1579-1583 ◽  
Author(s):  
J. Cadet
Keyword(s):  
Steady State ◽  
Aqueous Solutions ◽  
Hydroxyl Radical ◽  
Degradation Products ◽  
Ethylenic Bond ◽  
Decomposition Products ◽  
Radiation Induced ◽  
Radical Attack

Abstract The major radiation-induced degradation products of 5,6-dihydrothymine (1) in aqueous solutions saturated either with O2 or N2O/O2 (75/25 v/v) were identified as thymine (10), the trans-and cis-isomers of 6-hydroperoxy-5,6-dihydrothymine (5, 7), 5-hydroperoxy-5,6-dihydrothymine (9), and their corresponding hydroxy derivatives (4, 6, 8). The formation of these compounds is explained in terms of initial H-abstraction from the C(5) and C(6) carbons which gives rise respectively to the transient 5-yl and 6-yl radicals. Thymine hydroxy-hydroperoxides (11-14) and their decomposition products (17-20), which are derived from hydroxyl radical attack at the 5,6-ethylenic bond of thymine (10), were also characterized.

Functional characterization of human brown adipose tissue metabolism

2020 ◽  
Vol 477 (7) ◽  
pp. 1261-1286 ◽  
Author(s):  
Marie Anne Richard ◽  
Hannah Pallubinsky ◽  
Denis P. Blondin
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Functional Characterization ◽  
Human Infants ◽  
Positron Emission ◽  
Brown Adipose ◽  
Treatment Of Obesity ◽  
And Function

Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.

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