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36-444: Fmoc- carbamate is frequently used as a protecting group for primary and secondary amines , where the Fmoc group can be introduced by reacting the amine with fluorenylmethyloxycarbonyl chloride (Fmoc-Cl), e.g.: The other common method for introducing the Fmoc group is through 9-fluorenylmethylsuccinimidyl carbonate (Fmoc-OSu), which may itself be obtained by the reaction of Fmoc-Cl with

72-529: A quaternary ammonium group with a permanent positive charge, they have poor blood–brain barrier penetration, and also are only stable as crystalline salts or aqueous solutions, and so were not considered to have suitable properties for weaponisation. Iodopropynyl butylcarbamate is a wood and paint preservative and used in cosmetics. Some of the most common amine protecting groups, such as Boc , Fmoc , benzyl chloroformate and trichloroethyl chloroformate are carbamates. Urethane ( ethyl carbamate )

108-406: A BCAA-restricted diet decreased fasting blood glucose levels and improved body composition. Dietary valine is essential for hematopoietic stem cell (HSC) self-renewal, as demonstrated by experiments in mice. Dietary valine restriction selectively depletes long-term repopulating HSC in mouse bone marrow. Successful stem cell transplantation was achieved in mice without irradiation after 3 weeks on

144-509: A carbamate functional group. Ephedroxane , an aminorex analogue used as a stimulant , also falls into the carbamate category. Besides inhibiting human acetylcholinesterase (although to a lesser degree than the insect enzyme), carbamate insecticides also target human melatonin receptors. The human health effects of carbamates are well documented in the list of known endocrine disruptor compounds. Clinical effects of carbamate exposure can vary from slightly toxic to highly toxic depending on

180-433: A carbamate, this post-translational modification is known as carbamylation. This modification is known to occur on several important proteins; see examples below. The N-terminal amino groups of valine residues in the α- and β-chains of deoxyhemoglobin exist as carbamates. They help to stabilise the protein when it becomes deoxyhemoglobin, and increases the likelihood of the release of remaining oxygen molecules bound to

216-432: A description of Dumas's work by Henry Medlock. Medlock states "It is well known that the action of ammonia on chloro-carbonate (phosgene) of ethyl gives rise to the formation of the substance which Dumas, the discoverer, called urethane, and which we are now in the habit of considering as the ether of carbamic acid." This suggests that instead of continuing with the urethane family naming convention Dumas coined, they altered

252-442: A new substance endowed with interesting properties." Dumas appears to be naming this compound urethane. However, later Dumas states "While waiting for opinion to settle on the nature of this body, I propose to designate by the names of urethane and oxamethane the two materials which I have just studied, and which I regard as types of a new family, among nitrogenous substances . These names which, in my eyes, do not prejudge anything in

288-406: A usage that is strictly correct only for the ethyl esters." But also states, "An alternative term for the compounds R2NC(=O)OR' (R' not = H), esters of carbamic acids, R,NC(=O)OH, in strict use limited to the ethyl esters, but widely used in the general sense". IUPAC provides these statements without citation. Valine Valine (symbol Val or V ) is an α- amino acid that is used in

324-465: A variety of factors including such as dose and route of exposure with ingestion and inhalation resulting in the most rapid clinical effects. These clinical manifestations of carbamate intoxication are muscarinic signs, nicotinic signs, and in rare cases central nervous system signs. There are two oxygen atoms in a carbamate ( 1 ), ROC(=O)NR 2 , and either or both of them can be conceptually replaced by sulfur . Analogues of carbamates with only one of

360-590: A wide range of properties and are commercially available as foams, elastomers , and solids. Typically, polyurethane polymers are made by combining diisocyanates, e.g. toluene diisocyanate , and diols , where the carbamate groups are formed by reaction of the alcohols with the isocyanates : The so-called carbamate insecticides feature the carbamate ester functional group. Included in this group are aldicarb ( Temik ), carbofuran (Furadan), carbaryl (Sevin), ethienocarb , fenobucarb , oxamyl , and methomyl . These insecticides kill insects by reversibly inactivating

396-435: Is encoded by all codons starting with GU (GUU, GUC, GUA, and GUG). Valine was first isolated from casein in 1901 by Hermann Emil Fischer . The name valine comes from its structural similarity to valeric acid , which in turn is named after the plant valerian due to the presence of the acid in the roots of the plant. According to IUPAC , carbon atoms forming valine are numbered sequentially starting from 1 denoting

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432-421: Is a substituted carbamate. Besides their common use as arthropodocides/insecticides, they are also nematicidal . One such is Oxamyl . Sales have declined dramatically over recent decades. Among mutations in esterases , carbamate resistance most commonly involves acetylcholinesterase (AChE) desensitization, while organophosphate resistance most commonly is carboxylesterase metabolization. While

468-472: Is based on the natural alkaloid physostigmine . Other examples are meprobamate and its derivatives like carisoprodol , felbamate , mebutamate , phenprobamate , and tybamate , a class of anxiolytic and muscle relaxant drugs widely used in the 1960s before the rise of benzodiazepines, and still used nowadays in some cases. Carbachol is primarily used for various ophthalmic purposes. The protease inhibitor darunavir for HIV treatment also contains

504-583: Is formed when an uncharged lysine side chain near the ion reacts with a carbon dioxide molecule from the air ( not the substrate carbon dioxide molecule), which then renders it charged, and, therefore, able to bind the Mg ion. Although not usually isolated as such, the salt ammonium carbamate is produced on a large scale as an intermediate in the production of the commodity chemical urea from ammonia and carbon dioxide . Polyurethanes contain multiple carbamate groups as part of their structure. The "urethane" in

540-455: Is generated by treatment of ammonia with carbon dioxide : Carbamate esters also arise via alcoholysis of carbamoyl chlorides : Alternatively, carbamates can be formed from chloroformates and amines : Carbamates may be formed from the Curtius rearrangement , where isocyanates formed are reacted with an alcohol. Within nature carbon dioxide can bind with neutral amine groups to form

576-581: The branched-chain α-ketoacid dehydrogenase complex . This is further oxidised and rearranged to succinyl-CoA , which can enter the citric acid cycle and provide direct fuel in muscle tissue. Racemic valine can be synthesized by bromination of isovaleric acid followed by amination of the α-bromo derivative. The degradation of valine is impaired in the following metabolic diseases : Lower levels of serum valine, like other branched-chain amino acids, are associated with weight loss and decreased insulin resistance : higher levels of valine are observed in

612-452: The carboxyl carbon, whereas 4 and 4' denote the two terminal methyl carbons. Valine, like other branched-chain amino acids, is synthesized by bacteria and plants, but not by animals. It is therefore an essential amino acid in animals, and needs to be present in the diet. Adult humans require about 24 mg/kg body weight daily. It is synthesized in plants and bacteria via several steps starting from pyruvic acid . The initial part of

648-534: The ester ethyl carbamate ), formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups ; as well as salts with the carbamate anion H 2 NCOO (e.g. ammonium carbamate ). Polymers whose repeat units are joined by carbamate like groups −NH−C(=O)−O− are an important family of plastics , the polyurethanes . See § Etymology for clarification. While carbamic acids are unstable, many carbamate esters and salts are stable and well known. In water solutions,

684-716: The acid of carbamate, or carbamic acids . Although, a urethane has the same chemical structure as a carbamate ester moiety, a urethane not derived from a carbamic acid is not a carbamate ester. In other words, any synthesis of the R2NC(=O)OR' (R' not = H) moiety that does not derive from carbamic acids is not a carbamate ester but instead a urethane. Furthermore, carbamate esters are urethanes but not all urethanes are carbamate esters. This further suggests that polyurethanes are not simply polycarbamate-esters because polyurethanes are not typically synthesized using carbamic acids. IUPAC states "The esters are often called urethanes or urethans,

720-463: The acid-labile linker between the peptide and the resin. A typical SPPS Fmoc deprotection is performed with a solution of 20% piperidine in N,N-dimethylformamide (DMF). Carbamate In organic chemistry , a carbamate is a category of organic compounds with the general formula R 2 NC(O)OR and structure >N−C(=O)−O− , which are formally derived from carbamic acid ( NH 2 COOH ). The term includes organic compounds (e.g.,

756-538: The biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH 3 form under biological conditions), an α- carboxylic acid group (which is in the deprotonated −COO form under biological conditions), and a side chain isopropyl group , making it a non-polar aliphatic amino acid. Valine is essential in humans, meaning the body cannot synthesize it; it must be obtained from dietary sources which are foods that contain proteins , such as meats, dairy products, soy products, beans and legumes. It

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792-602: The blood of diabetic mice, rats, and humans. Mice fed a BCAA-deprived diet for one day had improved insulin sensitivity, and feeding of a valine-deprived diet for one week significantly decreases blood glucose levels. In diet-induced obese and insulin resistant mice, a diet with decreased levels of valine and the other branched-chain amino acids resulted in a rapid reversal of the adiposity and an improvement in glucose-level control. The valine catabolite 3-hydroxyisobutyrate promotes insulin resistance in mice by stimulating fatty acid uptake into muscle and lipid accumulation. In mice,

828-748: The carbamate acetylcholinesterase inhibitors are commonly referred to as "carbamate insecticides" due to their generally high selectivity for insect acetylcholinesterase enzymes over the mammalian versions, the most potent compounds such as aldicarb and carbofuran are still capable of inhibiting mammalian acetylcholinesterase enzymes at low enough concentrations that they pose a significant risk of poisoning to humans, especially when used in large amounts for agricultural applications. Other carbamate based acetylcholinesterase inhibitors are known with even higher toxicity to humans, and some such as T-1123 and EA-3990 were investigated for potential military use as nerve agents . However, since all compounds of this type have

864-450: The carbamate anion slowly equilibrates with the ammonium NH 4 cation and the carbonate CO 3 or bicarbonate HCO 3 anions: Calcium carbamate is soluble in water, whereas calcium carbonate is not. Adding a calcium salt to an ammonium carbamate/carbonate solution will precipitate some calcium carbonate immediately, and then slowly precipitate more as the carbamate hydrolyzes. The salt ammonium carbamate

900-555: The dicyclohexylammonium salt of N -hydroxysuccinimide . Reacting with 9-fluorenylmethyloxycarbonyl azide (itself made by reacting Fmoc-Cl with sodium azide ) in sodium bicarbonate and aqueous dioxane is also a method to install Fmoc group. Because the fluorenyl group is highly fluorescent , certain UV-inactive compounds may be reacted to give the Fmoc derivatives, suitable for analysis by reversed phase HPLC . Analytical uses of Fmoc-Cl that do not use chromatography may be limited by

936-404: The enzyme acetylcholinesterase (AChE inhibition) (IRAC mode of action 1a). The organophosphate pesticides also inhibit this enzyme, although irreversibly, and cause a more severe form of cholinergic poisoning (the similar IRAC MoA 1b). Fenoxycarb has a carbamate group but acts as a juvenile hormone mimic , rather than inactivating acetylcholinesterase. The insect repellent icaridin

972-469: The most prevalent carbamate is the one involved in the capture of CO 2 by plants. This process is necessary for their growth. The enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) fixes a molecule of carbon dioxide as phosphoglycerate in the Calvin cycle . At the active site of the enzyme, a Mg ion is bound to glutamate and aspartate residues as well as a lysine carbamate. The carbamate

1008-463: The name "polyurethane" refers to these carbamate groups; the term "urethane links" describe how carbamates polymerize . In contrast, the substance commonly called "urethane", ethyl carbamate , is neither a component of polyurethanes, nor is it used in their manufacture. Urethanes are usually formed by reaction of an alcohol with an isocyanate . Commonly, urethanes made by a non-isocyanate route are called carbamates . Polyurethane polymers have

1044-452: The naming convention to ethyl ether of carbamic acid. Carbamate is derived from the words "carbamide", otherwise known as urea, and "-ate" a suffix which indicates the salt or ester of an acid. Both words have roots deriving from urea. Carbamate is less-specific because the -ate suffix is ambiguous for either the salt or ester of a carbamic acid. However, the -ate suffix is also more specific because it suggests carbamates must be derived from

1080-512: The oxygens replaced by sulfur are called thiocarbamates ( 2 and 3 ). Carbamates with both oxygens replaced by sulfur are called dithiocarbamates ( 4 ), RSC(=S)NR 2 . There are two different structurally isomeric types of thiocarbamate: O -thiocarbamates can isomerise to S -thiocarbamates, for example in the Newman–Kwart rearrangement . [REDACTED] The etymology of the words "urethane" and "carbamate" are highly similar but not

1116-434: The pathway also leads to leucine . The intermediate α-ketoisovalerate undergoes reductive amination with glutamate . Enzymes involved in this biosynthesis include: Like other branched-chain amino acids, the catabolism of valine starts with the removal of the amino group by transamination , giving alpha-ketoisovalerate , an alpha- keto acid , which is converted to isobutyryl-CoA through oxidative decarboxylation by

Fluorenylmethyloxycarbonyl protecting group - Misplaced Pages Continue

1152-465: The protein. This stabilizing effect should not be confused with the Bohr effect (an indirect effect caused by carbon dioxide). The ε-amino groups of the lysine residues in urease and phosphotriesterase also feature carbamate. The carbamate derived from aminoimidazole is an intermediate in the biosynthesis of inosine . Carbamoyl phosphate is generated from carboxyphosphate rather than CO 2 . Perhaps

1188-420: The question of alcohol and ethers, will at least have the advantage of satisfying chemists who still refuse to accept our theory." The word urethane is derived from the words "urea" and "ether" with the suffix "-ane" as a generic chemical suffix, making it specific for the R2NC(=O)OR' (R' not = H) bonding structure. The use of the word "carbamate" appears to come later only being traced back to at least 1849, in

1224-545: The requirement that excess Fmoc-Cl be removed before an analysis of fluorescence. The Fmoc group is rapidly removed by base. Piperidine is usually preferred for Fmoc group removal as it forms a stable adduct with the dibenzofulvene byproduct, preventing it from reacting with the substrate. The use of Fmoc as a temporary protecting group for amine at the N-terminus in solid phase synthesis is very widespread for Fmoc/tBu approach, because its removal with piperidine does not disturb

1260-403: The same. The word "urethane" was first coined in 1833 by French chemist Jean-Baptiste Dumas. Dumas states "Urethane. The new ether, brought into contact with liquid and concentrated ammonia, exerts on this substance a reaction so strong that the mixture boils, and sometimes even produces a sort of explosion. If the ammonia is in excess, all the ether disappears. It forms ammonium hydrochlorate and

1296-502: Was once produced commercially in the United States as a chemotherapy agent and for other medicinal purposes. It was found to be toxic and largely ineffective. It is occasionally used in veterinary medicine in combination with other drugs to produce anesthesia . In addition, some carbamates are used in human pharmacotherapy , for example, the acetylcholinesterase inhibitors neostigmine and rivastigmine , whose chemical structure

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