Mechanisms by which cysteine can inhibit or promote the oxidation of low density lipoprotein by copper

Protective effects of endomorphins, endogenous opioid peptides in the brain, on human low density lipoprotein oxidation

“…The formation of lipid peroxidation products is a phenomenon common in most types of neurone damage associated with oxidative stress [7,10]. Cu 2+ ‐induced LDL peroxidation is generally monitored by UV spectroscopy since the primary peroxidation products of polyunsaturated fatty acids in LDL are hydroperoxides possessing a conjugated diene structure which shows characteristic UV absorption at 234 nm [41]. The rate of the chain propagation, R p , the inhibited rate of propagation by antioxidants, R inh , and the inhibition period, t inh , can be easily obtained from spectrophotometric data.…”

“…Blood collected into the anticoagulant EDTA (final concentration 3 m m ) was taken from healthy volunteers. LDL (1.019–1.063 g·mL −1 ) was isolated from the plasma by a discontinuous density gradient centrifugation procedure as described elsewhere [41] at 140 000 g for 6 h using a HITACHI 55P‐72 ultracentrifuge in KBr solution at 4 °C in the presence of EDTA (100 µ m ). The isolated LDL fraction was then dialysed with phosphate buffer (NaCl/P i pH 7.4) containing 100 µ m EDTA to prevent oxidation during dialysis.…”

“…The ability of endomorphins to inhibit Cu 2+ ‐mediated LDL oxidation was evaluated in quartz cuvettes through continuous spectrophotometric monitoring of absorbance increase at 234 nm, reflecting conjugated diene formation during peroxidative processes [41]. LDL (0.2 mg protein·mL ‐1 ) was incubated at 37 °C using a Shimadazu (Kyoto, Japan) model UV‐260 spectrophotometer.…”

Thiol oxidase ability of copper ion is specifically retained upon chelation by aldose reductase

“…Thiol oxidation induced by copper proceeds through the preliminary formation of complexes with different low molecular weight ligands, including the same thiol undergoing oxidation [34][35][36][37]. It is conceivable that the intramolecular copper complex characterizing Cu 1 -AR is more stable than the intermolecular complexes that copper may form with cysteine undergoing oxidation, which may explain the observed difference.…”

Homocysteine Levels in Takayasu Arteritis — A Risk Factor for Arterial Ischemic Events

“…Certain drugs may cause elevations in homocysteine levels, especially methotrexate (MTX) 13,14,15 . Cysteine is a semi-essential amino acid with structure and metabolic pathways similar to homocysteine, and both amino acids participate in the redox-thiol state that is important for antioxidant protection and in cardiovascular disease 19 . Some mechanisms proposed to explain how high homocysteine levels may contribute to the development of cardiovascular disease are endothelial dysfunction through the antagonizing nitric oxide effects, the production of oxygen-reactive species, impairment of paraoxonase 1 (PON1) activity, activation of smooth muscle cells, and increased thrombogenicity through deposition of Rheumatology The Journal of on June 12, 2015 -Published by www.jrheum.org Downloaded from fibrin on arterial walls 18 .…”