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Tryptophan Oxidation (tryptophan + oxidation)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Preparation of Novel Arrays Silver Nanoparticles Modified Polyrutin Coat-Paraffin-Impregnated Graphite Electrode for Tyrosine and Tryptophan's Oxidation

ELECTROANALYSIS, Issue 8 2008
Guan-Ping Jin
Abstract A novel array silver nanoparticles and Rutin complex film modified paraffin-impregnated graphite electrode was proposed in this work (denoted as Ag/Rutin/WGE). The characteristics were investigated by the field emission scanning electron microscopy (FE-SEM), infrared spectra (IR), UV-visible (UV), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Silver ions were gradually chelated by polyrutin film at 4,-oxo-5,-OH and 5-OH-4-oxo sites accompanying adsorption, then. Silver nanoparticles were highly-dispersed electrodeposited on polyrutin film. The electrochemical behaviors of tyrosine (Tyr) and tryptophan (Trp) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Ag/Rutin/WGE electrode shows overlapping catalysis for the oxidation of Tyr and Trp. The linear response of Tyr and Trp were 0.3,10.0 and 0.7,70.0,,M with detection limit of 0.07 and 0.1,,M in a signal-to-noise ratio of 3. [source]

Altered kynurenine metabolism correlates with infarct volume in stroke

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007
L. G. Darlington
Abstract Inflammation and oxidative stress are involved in brain damage following stroke, and tryptophan oxidation along the kynurenine pathway contributes to the modulation of oxidative stress partly via the glutamate receptor agonist quinolinic acid and antagonist kynurenic acid, and via redox-active compounds such as 3-hydroxyanthranilic acid. We have confirmed that following a stroke, patients show early elevations of plasma neopterin, S100B and peroxidation markers, the latter two correlating with infarct volume assessed from computed tomography (CT) scans, and being consistent with a rapid inflammatory response. We now report that the kynurenine pathway of tryptophan metabolism was also activated, with an increased kynurenine : tryptophan ratio, but with a highly significant decrease in the ratio of 3-hydroxyanthranilic acid : anthranilic acid, which was strongly correlated with infarct volume. Levels of kynurenic acid were significantly raised in patients who died within 21 days compared with those who survived. The results suggest that increased tryptophan catabolism is initiated before or immediately after a stroke, and is related to the inflammatory response and oxidative stress, with a major change in 3-hydroxyanthranilic acid levels. Together with previous evidence that inhibiting the kynurenine pathway reduces brain damage in animal models of stroke and cerebral inflammation, and that increased kynurenine metabolism directly promotes oxidative stress, it is proposed that oxidative tryptophan metabolism may contribute to the oxidative stress and brain damage following stroke. Some form of anti-inflammatory intervention between the rise of S100B and the activation of microglia, including inhibition of the kynurenine pathway, may be valuable in modifying patient morbidity and mortality. [source]

Kinetics of tryptophan oxidation in plasma lipoproteins by myeloperoxidase-generated HOCl

FEBS JOURNAL, Issue 13 2000
Andreas Jerlich
The relative susceptibility of the apoprotein components of human lipoproteins [high-density lipoprotein (HDL) and low-density lipoprotein (LDL)] and their subclasses to oxidation by the myeloperoxidase/H2O2/Cl, system in vitro was studied by measuring the decrease in rate of tryptophan fluorescence. Whereas the lipoprotein-modification rate showed a saturation type of dependence on the concentration of myeloperoxidase, a biphasic dependence on the concentration of the lipoproteins was found. High concentrations of H2O2 were also found to inhibit tryptophan oxidation in LDL but to a lesser extent in HDL. The optimal rate of LDL and HDL modification was observed at pH 6.0. HDL was modified much more rapidly than LDL, which may be due to differences in size and different relative contents of protein and lipids per particle. No differences in rates of modification of LDL subclasses were observed, when the assays were standardized to equal LDL protein concentrations, but, when standardized to equal particle mass, an optimum at subclass 8 was found, which is probably due to differences in apolipoprotein B-100 conformation. It was concluded that HDL may have a beneficial effect in retarding LDL modification in inflammatory processes. [source]