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Topic: Cysteine


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In the News (Thu 18 Jul 19)

  
  Cysteine - Wikipedia, the free encyclopedia
Cysteine is a naturally occurring amino acid which has a thiol group and is found in most proteins, though only in small quantities.
Cysteine contains a highly nucleophilic thiol group, and one of its primary purposes is to act as a nucleophilic catalyst.
Cysteine is required by sheep in order to produce wool, however it is an essential amino-acid that cannot be synthesised by the sheep and must be taken in as food from grass.
en.wikipedia.org /wiki/Cysteine   (764 words)

  
 cysteine. The Columbia Encyclopedia, Sixth Edition. 2001-05   (Site not responding. Last check: 2007-11-06)
A major complication of cystinuria, an inherited metabolic disease, one of whose symptoms is a twentyfold to thirtyfold increase in urinary excretion of cystine, is the precipitation of this relatively insoluble amino acid in the kidney, impairing its function.
Cystine was isolated from a urinary calculus in 1810 and from horn tissue in 1899.
Neither cysteine nor cystine is essential to the diet of man; cystine and cysteine are interconvertible, and cysteine is made in the body from serine and methionine.
www.bartleby.com /65/cy/cysteine.html   (352 words)

  
 Cysteine
Cysteine is a nonessential amino acid, which means that it is manufactured from other amino acids in the liver; it does not have to be obtained directly through the diet.
Cysteine is incorporated in the cellular glutathione, which works along with vitamin E to protect cells against free radical oxidant damage.
Cysteine is not only an essential constituent of proteins, but it also lies in the major route of incorporation into all organic sulfur compounds in the body.
www.springboard4health.com /notebook/proteins_cysteine.html   (513 words)

  
 Cysteine protease - Wikipedia, the free encyclopedia
Cysteine proteases have a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad.
In this step, a fragment of the substrate is released with an amine terminus, the histidine residue in the protease is restored to its deprotonated form, and a thioester intermediate linking the new carboxy-terminus of the substrate to the cysteine thiol is formed.
The thioester bond is subsequently hydrolyzed to generate a carboxylic acid moiety on the remaining substrate fragment, while regenerating the free enzyme.
en.wikipedia.org /wiki/Cysteine_protease   (277 words)

  
 N-Acetyl Cysteine Crystals, Vitamin Nac, Cystine Stones
Cysteine is considered a non-essential amino acid because it is formed from methionine in the body.
Cysteine may be metabolized by several routes to yield pyruvate, taurine, or sulfide and sulfate.
Cysteine is also a precursor to gultathione, a substance that detoxifies the liver by binding with potentially harmful substances there.
www.wellfx.com /InfoBase/vitamin_cysteine_.htm   (1348 words)

  
 L-Cysteine
Cysteine's protective mechanisms could relate to its own antioxidant properties, its promotion of glutathione (a major antioxidant) or even, it has been hypothesized, to some ability to participate in DNA repair.
Regulation by the antioxidants ascorbate, cysteine, and dapsone of the increased extracellular and intracellular generation of reactive oxidants by activated phagocytes from cigarette smokers.
Effect of cysteine on the survival of mice with transplanted malignant lymphoma.
www.pdrhealth.com /drug_info/nmdrugprofiles/nutsupdrugs/lcy_0088.shtml   (999 words)

  
 Cysteine   (Site not responding. Last check: 2007-11-06)
CYSTEINE is a non-essential, sulphur-containing amino acid that is the principal source of sulphur in the diet.
Cysteine's most important function is to contribute to the structure of proteins in the form of cystine.
Cysteine and methionine are used to form several essential compounds, including coenzyme A, heparin, biotin, lipoic acid, and glutathione.
www.innvista.com /HEALTH/nutrition/amino/cysteine.htm   (515 words)

  
 Cysteine amino acid information page. All about cysteine and the role it plays in your diet.
Cysteine is a sulfur containing non-essential amino acid and is closely related to cystine, as cystine consists of two cysteine molecules joined together.
Cysteine is also required in the manufacture of the amino acid taurine and is a component of the antioxidant gluthione.
Cysteine is also critical to the metabolism of a number of essential biochemicals including coenzyme A, heparin, biotin, lipoid acid, and glutathione.
www.anyvitamins.com /cysteine-info.htm   (516 words)

  
 N101 | Cysteine   (Site not responding. Last check: 2007-11-06)
Cysteine is a nonessential amino acid (protein building block), meaning that cysteine can be made in the human body.
Cysteine, the amino acid from which NAC is derived, is found in most high-protein foods.
Cysteine has a role in the proper function of the immune system, so a deficiency of this amino acid may either contribute to, or result from, immune suppression associated with HIV.
www.n101.com /Static/HNs/Supp/Cysteine.htm   (686 words)

  
 cysteine at cysteine.kras.tychy.pl   (Site not responding. Last check: 2007-11-06)
Also, chicken soup contains cysteine, an amino acid in chicken that is chemically similar to a drug used to treat bronchitis.
Cysteine amino acids are sulfur-based and Mercury will bind to them.
Tribune - This small sub-molecular replacement results in the replacement of an amino acid called Arginine by Cysteine which consequently modifies the structure of the alpha-crystallin that is synthesized by this gene and which is an essential lens protein...
cysteine.kras.tychy.pl   (391 words)

  
 Comprehensive Nutrient Review: L-Cysteine Research Abstracts
Cysteine sulfinic acid, a cysteine metabolite, is a poorer substrate for horseradish peroxidase than cysteine and is oxidized to form both sulfur-centered and carbon-centered free radicals.
Because oral cysteine per se is considerably more protective than the in vivo metabolic cysteine precursors, methionine or cystine, chelation of cysteine with trace elements likely occurs primarily in the gut, thereby decreasing absorption of both cysteine and the trace element in question.
Cysteine or cysteine derivatives may therefore be considered for the treatment of patients with HIV-1 infection.
www.lef.org /abstracts/codex/l-cysteine_abstracts.htm   (6209 words)

  
 Cysteine
Low levels of cysteine may be linked to an increased risk of cervical dysplasia (changes to the opening of the uterus, that are precancerous or cancerous).
Cysteine is also found in most high-protein foods including ricotta, cottage cheese, yogurt, pork, sausage meat, chicken, turkey, duck, luncheon meat, wheat germ, granola, and oat flakes.
Cysteine supplements should not be taken by individuals with cystinuria, a kidney condition in which excessive amounts of cysteine (along with three other amino acids) are lost in the urine.
www.umm.edu /altmed/ConsSupplements/Cysteinecs.html   (2299 words)

  
 The World's Healthiest Foods: cysteine
Cysteine is a sulfur-containing amino acid that occurs naturally in foods and can also be manufactured by the body from the amino acid methionine.
Glutathione, formed from cysteine, glutamic acid, and glycine, is found in all human tissues, with the highest concentrations found in the liver and eyes.
Cysteine deficiency is relatively uncommon, but may be seen in vegetarians with low intake of the plant foods containing methionine and cysteine.
www.whfoods.com /genpage.php?tname=nutrient&dbid=54   (1061 words)

  
 Clinical Trial: Cysteine Supplementation in Critically Ill Neonates
Cysteine has effectively become a safe and standard supplement to routine TPN in a few major hospitals in the U.S. The purpose of this study is to evaluate the ability of cysteine supplementation to increase glutathione production and concentrations in critically ill babies.
Cysteine is considered to be a conditionally essential amino acid for neonates and is the rate limiting substrate for the synthesis of glutathione.
Although cysteine is a non-essential amino acid made from methionine via cystathionine in children and adults, most premature and term neonates have a decreased capacity to synthesize cysteine due to their low expression of the rate limiting enzyme cystathionase.
www.clinicaltrials.gov /ct/show/NCT00254176   (2148 words)

  
 Amino Acids - Alanine
Cysteine is one of two sulfur-containing amino acids; the other is methionine.
Cysteine differs from serine in a single atom-- the sulfur of the thiol replaces the oxygen of the alcohol.
Furthermore, the proton of the thiol of cysteine is much more acid than the hydroxylic proton of serine, making the nucleophilic thiol(ate) much more reactive than the hydroxyl of serine.
www.biology.arizona.edu /biochemistry/problem_sets/aa/Cysteine.html   (210 words)

  
 L-cysteine
Cysteine is a sulfur containing amino that detoxifies many harmful chemicals including those from cigarette smoke, pollution and alcohol as well as copper and heavy toxic metals.
Since Cysteine is a central amino in the protein keratin, it has been found to increase hair growth by as much as 100%, to increase the diameter of hair shafts and to harden the nails.
Cysteine is a powerful antioxidant that has been shown to help protect the cells against X-Ray and nuclear radiation.
www.betterbodz.com /library/l_cysteine.html   (150 words)

  
 Cysteine and L-cysteine   (Site not responding. Last check: 2007-11-06)
Although most cysteine is found in proteins, small amounts of cysteine are also located in body fluids and in plants in non-protein form.
Cysteine can also be transformed into glucose and used by the body as a source of energy.
Cysteine is rarely used as a dietary supplement.
www.nutrasanus.com /cysteine.html   (489 words)

  
 MoonDragon's Health & Wellness: Nutrition - Amino Acids: Cysteine & Cystine
Cysteine is present in alpha-keratin, the chief protein constituent of the fingernails, toenails, skin, and hair.
Cysteine also assists in the supply of insulin to the pancreas, which is needed for the assimulation of sugars and starches.
Cysteine is only incorporated into proteins at the rate of 2.8 percent relative to the other amino acids, but the unique thiol side chain of this amino acid is often heavily involved in the three-dimensional stability of proteins and enzymes.
www.moondragon.org /health/nutritionbasics/aminoacids/cystine.html   (1477 words)

  
 Diagnose-Me: Treatment: Cysteine / N-Acetyl-Cysteine (NAC)
N-acetyl cysteine (NAC) is an altered form of the non-essential amino acid cysteine, which is commonly found in food and synthesized by the body.
Indications are that it is anti-aging; anti-oxidant; a powerful aid in protecting the body from radiation; it deactivates free radicals; is vital for the formation of skin and cell recovery particularly after surgery or cellular damage from burns.
Cysteine is a sulfur-bearing amino acid with antioxidant properties.
www.diagnose-me.com /treat/T292370.html   (860 words)

  
 Cysteine Molecule
Cysteine is a naturally occurring hydrophilic ("water loving")
Cysteine aids in Phase II Detoxification pathway in the liver.
Cysteine also aids the metabolism of biochemicals such as heparin, biotin, coenzyme A and glutathione.
www.worldofmolecules.com /life/cysteine.htm   (93 words)

  
 Pyruvate Released by Astrocytes Protects Neurons from Copper-Catalyzed Cysteine Neurotoxicity -- Wang and Cynader 21 ...
The reaction conditions to assess cysteine autoxidation were 37°C and pH 7.4 in a humidified atmosphere of 5% CO and 95% air.
Cysteine and related compounds were incubated in PBS under the conditions of pH 7.4 and 37°C in a humidified atmosphere of 100% air.
Cysteine, as well as glutathione or other thiols, will be oxidized to disulfide under the catalysis of protein-unbound or loosely bound copper.
www.jneurosci.org /cgi/content/full/21/10/3322   (6265 words)

  
 Amino Acid Metabolism
In cysteine synthesis, homocysteine condenses with serine to produce cystathionine, which is subsequently cleaved by cystathionase to produce cysteine and a-ketobutyrate.
Cysteine is used for protein synthesis and other body needs, while the a-ketobutyrate is decarboxylated and converted to propionyl-CoA.
Cystathionase is under negative allosteric control by cysteine, as well, cysteine inhibits the expression of the cystathionine synthase gene.
web.indstate.edu /thcme/mwking/amino-acid-metabolism.html   (3903 words)

  
 Smart Basics - N-Acetyl Cysteine ( NAC ) is a powerful antioxidant and a premier antitoxin: Smart Basics   (Site not responding. Last check: 2007-11-06)
N-Acetyl Cysteine has been shown to provide protection against free radicals as well as a broad range of toxic hazards such as: acrolein (found in barbecue and cigarette smoke and auto exhaust), bromobenzene, paraquat (a toxic herbicide), overdoses of acetaminophen, and the side-effects of cyclophosphamide and adrimycin (anti-cancer drugs).
The key to this protection may be the sulfur and sulfhydryl groups contained in N-Acetyl Cysteine and its derivative, Glutathione.
N-Acetyl Cysteine is also a better source of glutathione than taking glutathione itself, because less than half of supplementalt glutathione gets out of the digestive system and into the body.
www.ehot.com /smartbasics/nac_cat.html   (387 words)

  
 cysteine   (Site not responding. Last check: 2007-11-06)
Cysteine, an amino acid, is the precursor to glutathione (a powerful antioxidant and important detoxifying agent).
N-acetylcysteine, a synthetic precursor of cysteine, is commonly used as a mucolytic agent and as an antidote against acetaminophen-induced hepatotoxicity.
Women in the highest level of plasma cysteine group had a significant 56 percent reduction in risk of developing breast cancer as compared with those in the lowest level group.
www.youngagain.com /cysteine.html   (818 words)

  
 Glutathione, GSH and Whey Protein. Information for Physicians
Cysteine is a sulfur-containing (sulfhydryl) amino acid which is present in many proteins, and is in the same class as methionine.
Cysteine is an important source of sulfur in human metabolism, and although it is classified as a non-essential amino acid, cysteine may be essential for infants, and may at some point be recognized as an essential or conditionally essential amino acid.
It is the sulfhydryl (thiol) group (SH) of cysteine that serves as proton-donor and is responsible for the biological activity of glutathione.
www.nutritionadvisor.com /glutathione.html   (3206 words)

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