Search results for "Cystine"
showing 10 items of 29 documents
The Crystal Structure of Gurmarin, a Sweet Taste–Suppressing Protein: Identification of the Amino Acid Residues Essential for Inhibition
2018
International audience; Gurmarin is a highly specific sweet-taste suppressing protein in rodents that is isolated from the Indian plant Gymnemasylvestre. Gurmarin consists of 35 amino acid residues containing three intramolecular disulfide bridges that form a cystine knot. Here, we report the crystal structure of gurmarin at a 1.45 Å resolution and compare it with previously reported NMR solution structures. The atomic structure at this resolution allowed us to identify a very flexible region consisting of hydrophobic residues. Some of these amino acid residues had been identified as a putative binding site for the rat sweet taste receptor in a previous study. By combining alanine-scanning …
Can aminothiols be distinguished from reactive oxygen species?
2016
Glutathione is considered the major natural antioxidant, protecting cells from oxidative stress. Patel and colleagues used plasma levels of the aminothiols cystine and glutathione to quantify oxidative stress in patients with coronary artery disease, and show that the cystine/glutathione ratio is associated with increased mortality. Is this a new approach for clinical risk stratification?
Elevated plasma total homocysteine in centenarians
2004
Homocysteine (Hcy) is a sulfur-containing metabolite of methionine and is an emerging independent risk factor for atherosclerosis. Previous studies have shown that age, gender, renal function and folic acid intake are the main factors influencing total plasma Hcy levels in humans. A unique approach to the science of human longevity is the natural model of centenarians. The objective of this study was to verify whether the previously determined risk factors for atherosclerosis and atherosclerosis-related diseases change with age and, finally, to establish the vitamin nutritional status role. We studied 54 centenarians (14 males and 40 females) aged between 100-107 years (mean age 102.6+/-1.8…
Association between M467T and 114 C--A variants within the SLC3A1 gene and some phenotypical traits in cystinuria patients from Spain.
2000
Cystinuria is an inherited metabolic disease characterized by an abnormal urinary excretion of cystine and dibasic amino acids. Formation of renal calculi, recurrent infections and renal failure are the main complications of this disease. The SLC3A1 gene, which codes for a dibasic amino acid transporter protein, is involved in the pathogenesis of cystinuria. We investigated the possible association between molecular variants (M467T, E483X, T216 M and 114 C--A) within the SLC3A1 gene and some phenotypical traits in a Spanish area. The study population consisted of 45 cystinuria patients, 42 cystinuria relatives and 81 healthy control subjects. Only the M467T mutation was found in chromosomes…
Homodimeric murine interleukin-3 agonists indicate that ligand dimerization is important for high-affinity receptor complex formation.
1994
Homodimeric murine interleukin 3 (mIL-3) agonists were generated by intermolecular cystine-bonding. Steady-state binding assays and association kinetics performed at 4 degrees C using these agonists revealed specific binding to both the high- and low-affinity receptor. DSS-mediated crosslinking studies performed at 4 degrees C with agonist concentrations compatible with high-affinity receptor complex formation allowed to detect protein complexes of the alpha chain, the beta chain(s) and the high-affinity receptor complex migrating with apparent molecular weights of 90 kDa, 140 kDa, and above 180 kDa, respectively. In contrast, monomeric mIL-3 was crosslinked to the alpha chain receptor only…
Inhibition of the hydrolytic and transpeptidase activities of rat kidney gamma-glutamyl transpeptidase by specific monoclonal antibodies
1999
Monoclonal antibodies (mAb) against the native form of rat kidney gamma-glutamyl transpeptidase (GGT) were isolated by screening hybridomas with rat kidney brush-border membrane vesicles. They were directed against protein rather than sugar epitopes in that each recognized all GGT isoforms. All of them inhibited partially the enzyme activity of GGT. They were specific in that they inhibited the rat enzyme, but not the mouse or human enzyme. Kinetic analyses were carried out with free GGT and GGT-mAb complexes with d-gamma-glutamyl-p-nitroanilide in the presence or absence of maleate, or in the presence or absence of alanine, cysteine, cystine or glycylglycine as gamma-glutamyl acceptors. mA…
From Screening to Scale-Up: The DoE-Based Optimization of Electrochemical Reduction of l-Cystine at Metal Cathodes
2021
Design of experiment (DoE) is a powerful statistical tool in establishing improved chemical processes. An optimization and scale-up of the electrochemical reduction of l-cystine to l-cysteine is pr...
Biosynthesis and maintenance of GSH in primary astrocyte cultures: role of L-cystine and ascorbate.
1995
Abstract We have studied the optimal conditions to maintain the astrocyte GSH levels under normal and oxidative stress conditions. The rate of GSH synthesis from l -methionine was statistically lower than from l -cystine or N -acetyl-cysteine in astrocytes treated with diethyl-maleate, which is substrate of GSH S-transferases. This is in accordance with the fact that cystathionase activity was not detectable. The transport of l -cystine mediated by the Na + -independent system Xc − is the limiting step in GSH synthesis in astrocytes. Incubation with tert-butyl hydroperoxide (t-booH) reduced GSH concentration in astrocytes. This reduction was ameliorated in part by the addition of ascorbate …
Selective flow-injection biamperometric determination of sulfur-containing amino acids and structurally related compounds
2001
Abstract A simple and selective flow-injection method for the determination of cysteine and methionine is proposed. The method is based on the reaction of the amino acid with chloramine-T and the subsequent reaction of the excess of chloramine-T with an acidic solution of iodide producing a stoichiometric amount of tri-iodide (diminution of the flow-injection analysis (FIA) peak) which is determined biamperometrically using two platinum electrodes polarized at 100 mV. The calibration graph is linear up to 10 μg ml−1 of cysteine and 30 μg ml−1 of methionine; the limit of detection is 0.06 and 0.1 μg ml−1; the repeatability (also as percent of a series of 70 continuous FIA peaks of 5 μg ml−1 …