cystine


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cystine

 [sis´tēn, sis´tin]
a naturally occurring amino acid, the chief sulfur-containing component of the protein molecule. It is sometimes found in the urine and in the kidneys in the form of minute hexagonal crystals, frequently forming cystine calculus in the bladder.
cystine storage disease Fanconi's syndrome (def. 2).

cys·tine

(sis'tēn, sis'tin), Do not confuse this word with cysteine.
3,3'-Dithiobis(2-aminopropionic acid); the disulfide product of two cysteines in which two -SH groups become one -S-S- group; if two cysteinyl residues in polypeptide chains form a disulfide linkage, then the two polymers are cross-linked; sometimes occurs as a deposit in the urine, or forming a vesical calculus. Compare: meso-cystine.
Synonym(s): dicysteine

cystine

(sĭs′tēn′)
n.
A white crystalline amino acid, C6H12N2O4S2, that is formed from the disulfide linkage of two cysteines during the folding of many proteins, especially keratin, and stabilizes the tertiary structure of the protein.

cys·tine

(sis'tēn)
The disulfide product of two cysteines in which two -SH groups become one -S-S- group; sometimes occurs as a deposit in the urine, or forming a vesical calculus.
Cystineclick for a larger image
Fig. 127 Cystine . Formation of cystine.

cystine [Cys-Cys]

an amino acid residue formed by the OXIDATION of the sulphydryl groups [SH] of two CYSTEINES generating a DISULPHIDE BRIDGE (S-S); See Fig. 127 . In some PROTEINS, side chains can be cross-linked by disulphide bridges as a result of the formation of cystines. See SULPHUR BRIDGE.
References in periodicals archive ?
For prevention of calcium oxalate, cystine, and uric acid stones, urine should be alkalinized by eating a diet high in fruits and vegetables, taking supplemental or prescription citrate, or drinking alkaline mineral waters.
We found statistically significant correlations between increased resistance to itraconazole and higher enzymatic activity of naphthyl phosphohydrolase and alpha-galactosidase; increased resistance to fluconazole and higher enzymatic activity of trypsin and beta-glucosidase; increased susceptibility to 5-fluorocytosine and higher enzymatic activity of alkaline phosphatase, valine arylamidase, trypsin and chymotrypsin; increased susceptibility to ketoconazole and higher enzymatic activity of cystine arylamidase.
Impairment of the transporter system responsible for transporting cystine out of lysosomes results in the accumulation of cystine crystals in tissues such as the kidneys, eyes, bone marrow, liver, spleen, pancreas, thyroid, skeletal muscles, thyroid, and brain.
The goal of treatment in cystinuria is to prevent recurrence of stones by decreasing urinary cystine concentrations to below the solubility limit (< 250 mg/L) or increasing the solubility of cystine.
As seen in Figure 3, after an 88-day interval, the increase for cysteic acid and cystine dioxide is significantly higher than for other S-species.
If plasma homocysteine concentrations remain well controlled and if protein stores and growth parameters are of no concern but cystine levels are below the reference range, extra supplementation may offer little benefit.
Based upon the relative percentages for each of these four proteins within the whey protein fraction and the number of cystine or glutamylcysteine residues contained within each protein, we calculated the approximate concentration of each of these GSH precursors with which CGNs were treated (Table 3).
The mean lead levels of various types of calculi were found to follow the order as phosphate > oxalate > urate.> cystine while single principal group of supra gingival calculi resulted in lower levels of metal.
Zhou, Redox reactions of and transformation between cysteine-mercury thiolate and cystine in metallothioneins adsorbed at a thin mercury film electrode, Langmuir 17, 4081 (2001).
The disorder results from dysfunction or absence of the cystinosin protein, a lysosomal membrane transporter that serves to export cystine from the lumen of the lysosome (2, 3).
The effects of GanedenBC 30 with protein were examined in a random double blind crossover clinical trial on key amino acids including leucine (the regulator for muscle protein synthesis), isoleucine and valine (branched chain amino acids), as well as histidine, alanine, asparagines, citrulline, cystine, glutamine (a key amino acid for supporting ph balance and the immune system), methionine, ornthinine, serine, threonine, tryptophan and phenylalanine.
Similarly the effect of 0.01% amino acid solution of alanine, aspartic acid, cysteine, cystine, glutamine, histidine, leucine, lysine, tyrosine and thiamine supplemeted in basal medium was investigated.