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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).
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

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
Farlex Partner Medical Dictionary © Farlex 2012

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.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

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.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
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.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
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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.
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.
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.
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