- Degradation kinetics of L-glutamine in aqueous solution
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The degradation kinetics of L-glutamine (Gln) in aqueous solution was studied as a function of buffer concentration, pH and temperature. Stability tests were performed using a stability-indicating high-performance liquid chromatographic assay. The degradation product of Gln was 5-pyrrolidone-2-carboxylic acid. The reaction order for Gln in aqueous solution followed pseudo-first-order kinetics under all experimental conditions. The maximum stability of Gln was observed in the pH range from 5.0 to 7.5. The pH-rate profile described by specific acid-base catalysis and hydrolysis by water molecules agreed with the experimental results. Arrhenius plots showed the temperature dependence of Gln degradation, and the apparent activation energy at pH 6.41 was determined to be 9.87x104 J mol-1. Copyright (C) 1999 Elsevier Science B.V.
- Arii, Kanji,Kobayashi, Hideyuki,Kai, Toshiya,Kokuba, Yukifumi
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Read Online
- Phase transformations of glutamic acid and its decomposition products
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The thermal behavior and phase transformations of the α and β polymorphs of L-glutamic acid were studied by differential scanning calorimetry, thermogravimetry, powder X-ray diffraction, gel permeation chromatography, and mass spectrometry. Solid-state transformation of α to β polymorph was observed at temperatures above 140 °C, together with, in sequence, cyclization to pyroglutamic acid and polymerization to polyglutamic acid. The resulting polyglutamic acid is a high molecular weight amorphous polymer, with a glass transition temperature at 20 °C.
- Wu, Han,Reeves-McLaren, Nik,Jones, Simon,Ristic, Radoljub I.,Fairclough, J. Patrick A.,West, Anthony R.
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Read Online
- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
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A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
- Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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supporting information
p. 709 - 713
(2019/01/25)
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- Synthetic method of Boc-L-Pyroglutamic acid methyl ester
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The invention discloses a synthetic method of Boc-L-Pyroglutamic acid methyl ester. The synthetic method comprises the following steps: dissolving L-pyroglutamic acid into methanol, adding a catalyst thionyl chloride and reacting, adding sodium bicarbonate to stop the reaction and generating methyl L-pyroglutamate; dissolving Methyl L-pyroglutamate into dichloromethane, adding a catalyst DMAP, adding di-tert-butyl dicarbonate in batches, and reacting to generate Boc-L-Pyroglutamic acid methyl ester. By using L-pyroglutamic acid as a raw material for preparation of Boc-L-Pyroglutamic acid methyl ester, the method has advantages of simple operation and low cost. The Boc-L-Pyroglutamic acid methyl ester prepared by the method has high yield, and purity can reach 99.8%. The product can meet quality requirements of the market. Therefore, the method is simple to operate, is convenient to prepare, is low-cost, is green and environment friendly, has no harsh reaction condition, and is suitable for large-scale industrial production.
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Paragraph 0038; 0039; 0040
(2017/05/23)
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- Tert-Butyl Nitrite-Mediated Synthesis of N-Nitrosoamides, Carboxylic Acids, Benzocoumarins, and Isocoumarins from Amides
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This work reports tert-butyl nitrite (TBN) as a multitask reagent for (1) the controlled synthesis of N-nitrosoamide from N-alkyl amides, (2) hydrolysis of N-methoxyamides to carboxylic acids, (3) metal- and oxidant-free benzocoumarin synthesis from ortho-aryl-N-methoxyamides via N-H, C-N, and C-H bond activation, and (4) isocoumarin synthesis using Ru(II)/PEG as a recyclable catalytic system via ortho-C-H activation and TBN as an oxygen source. The sequential functional group interconversion of amide to acid has also been examined using IR spectroscopic analysis. Additionally, this methodology is highly advantageous due to short reaction time, gram scale synthesis, and broad substrate scope.
- Yedage, Subhash L.,Bhanage, Bhalchandra M.
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p. 5769 - 5781
(2017/06/07)
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- A L-villaggio glu preparation method (by machine translation)
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The invention discloses a preparation method of an L-pyroglutamic acid. The preparation method comprises the following steps: 1, melting, namely melting a L-glutamic acid serving as a raw material at a temperature ranging from 170 DEG C to 180 DEG C and under the pressure ranging from 0.45MP to 0.55MP; 2, cooling, namely after the temperature of the melt falls, feeding the melt into a cooling tank until the melt is completely coagulated into a block; 3, decoloring, namely putting the cooled block into mother liquor, increasing the temperature to the range of 70 DEG C to 75 DEG C and then adding activated carbon for decoloring; 4, filtering, namely filtering by use of a plate frame and remaining the filtrate for crystallization; 5, cooling the filtrate and separating out crystals; and 6, separating, namely putting the solid-liquid mixture after crystallization into a centrifugal separator to separate out the finished product L-pyroglutamic acid. Due to the adopted technical scheme of the preparation method of the L-pyroglutamic acid, the reaction temperature is reduced, and DL-pyroglutamic acid and other impurities are reduced; the production efficiency is improved; the production steps are reduced so that the cost is reduced; the quality and yield of the product are obviously improved and increased, and large-scale production can be realized.
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Paragraph 0026-0027; 0032; 0039
(2017/04/11)
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- Synthesis of biobased succinimide from glutamic acid via silver-catalyzed decarboxylation
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Glutamic acid was transformed into succinimide in a two step procedure involving a dehydration in water to pyroglutamic acid followed by an oxidative decarboxylation using a silver catalyst.
- Deng, Jin,Zhang, Qiu-Ge,Pan, Tao,Xu, Qing,Guo, Qing-Xiang,Fu, Yao
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p. 27541 - 27544
(2014/07/21)
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- Polypeptide formation by heating N-t-butyloxycarbonyl acidic amino acid derivatives
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An acid labile N-protecting group for amino acids, t-butyloxycarbonyl (Boc) group has deprotected at elevated temperatures. The study describes an application of the lability on heating to synthesis of polypeptides from acidic amino acids. t-Butyloxycarbonyl-acidic amino acids (aspartic acid, glutamic acid and β-aminoglutaric acid) and their anhydrides were heated at the higher temperatures than their melting points. Anhydrides of t-butyloxycarbonyl-aspartic acid and t-butyloxycarbonyl-β-aminoglutaric acid gave polypeptides. Thermal analyses of the substrates clarified the pathway of the polypeptide formation.
- Munegumi,Qing Meng,Harada
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p. 4716 - 4722
(2014/12/10)
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- Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
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An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
- Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
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supporting information
p. 4149 - 4151
(2014/07/22)
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- Total reflection fluorescent observation device
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A device and method for fluorescence observation have good operability, high sensitivity, and high acid reliability. The device is used for fluorescence observation using evanescent light. The angle of incidence of the excitation light is adjusted so that the excitation light is totally reflected from the surface of a substrate irrespective of the angle of the substrate surface. The method includes a step of shining the excitation light on the observation substrate while continuously varying the angle of the excitation light with respect to the observation substrate. In addition, the method includes a step of sensing the shone excitation light via optical sensors, and a step of setting the angle of total reflection according to the result of the sensing by the optical sensors. In the present device and method, the direction in which the shone excitation light travels varies with the angle of incidence.
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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- A mild Boc deprotection and the importance of a free carboxylate
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We report a facile and rapid removal of Boc protecting groups using microwave heating in H2O, with deprotection only requiring a free carboxylic acid group in the starting material. Unlike previous approaches, no additional reagents are required.
- Thaqi, Ali,McCluskey, Adam,Scott, Janet L.
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supporting information; experimental part
p. 6962 - 6964
(2009/04/07)
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- Anti-heparin peptides
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The invention concerns a compound exhibiting an anti-heparin activity, of formula Z Bm ! (AXA)x Bn ! (AXA)y Bo (AXA)z Bp, the diagnostic reagents comprising it and the use of said compound in an in vitro diagnostic test of a medicine for anti-heparin activity.
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- Methods and compositions for providing glutamine
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Methods and compositions for providing glutamine supplementation to a human by orally administering an effective amount of N-acetyl-L-glutamine or a nutritionally acceptable salt thereof. The N-acetyl L-glutamine or a nutritionally acceptable salt thereof can be incorporated into any liquid composition that is suitable for human consumption. Examples of suitable compositions include aqueous solutions such as for use as oral rehydration solutions and liquid nutritional formulas (including enteral formulas, oral formulas, formulas for adults, formulas for children and formulas for infants). The quantity of N-acetyl-L-glutamine or nutritionally acceptable salt thereof can vary widely but typically, these compositions will contain sufficient N-acetyl-L-glutamine or a nutritionally acceptable salt thereof to provide at least 140 mg of total glutamine per kg of body weight per day.
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- Methods and compositions for providing glutamine
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Methods and compositions for providing glutamine supplementation to a human by orally administering an effective amount of N-acetyl-L-glutamine or a nutritionally acceptable salt thereof. The N-acetyl L-glutamine or a nutritionally acceptable salt thereof can be incorporated into any liquid composition that is suitable for human consumption. Examples of suitable compositions include aqueous solutions such as for use as oral rehydration solutions and liquid nutritional formulas (including enteral formulas, oral formulas, formulas for adults, formulas for children and formulas for infants). The quantity of N-acetyl-L-glutamine or nutritionally acceptable salt thereof can vary widely but typically, these compositions will contain sufficient N-acetyl-L-glutamine or a nutritionally acceptable salt thereof to provide at least 140 mg of total glutamine per kg of body weight per day.
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- Microwave Promoted Synthesis of a Rehabilitated Drug: Thalidomide
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A new direct synthesis of thalidomide in high yield by microwave irradiation of N-phthaloyl-L-glutamic in the presence of thiourea is described. Thalidomide was also obtained in good yield from L-glutamic acid, phthalic anhydride and thiourea in a one-pot procedure.
- Seijas, Julio A.,Vazquez-Tato, M. Pilar,Gonzales-Bande, Cristobal,Martinez, M. Montserrat,Pacios-Lopez, Beatriz
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p. 999 - 1000
(2007/10/03)
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- Folic acid derivatives
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Novel folic acid derivatives and their use in preparation of γ-esters of folic acid via a pteroyl azide intermediate are described. Folic acid γ-esters are useful intermediates in the synthesis of folic acid conjugates capable of binding folate receptors in vitro and in vivo.
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- Process for the continuous production of basic cyclic optically active alpha - amino acids
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PCT No. PCT/EP96/04073 Sec. 371 Date Mar. 24, 1998 Sec. 102(e) Date Mar. 24, 1998 PCT Filed Sep. 18, 1996 PCT Pub. No. WO97/12881 PCT Pub. Date Apr. 10, 1997The invention pertains to a process for the continuous production of basic cyclic optically active alpha -amino acids of general formula (I) by continuous racemate splitting via diastereomeric salt pairs with re-racemisation of the residual amino acid or amino acid derivative in the mother liquid with the aid of an optically active acid.
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- Aminopyri(mi)dine derivatives combined with amino acids, and pharmacological activities thereof
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Synthetic compounds combining sulphur-containing or sulphur-free amino acids with aminopyrimidine and aminopyridine derivatives, as well as mineral or organic acid addition salts produced in the presence of an amino grouping, were synthesized. Non-sulphur amino acids such as glutamic acid, pyroglutamic acid, tyrosine, histidine and arginine, and sulphur amino acids such as methionine, cysteine, S-methyl-cysteine and cystine, were attached to minoxidil to give monosubstituted and disubstituted derivatives. The amides with a pyrimidine or pyridine structure coupled to an amide structure in which the carbonyl is from sulphur-containing or sulphur-free amino acid have the properties of; (1) excellent adhesion to the skin, particularly the epidermis; (2) capturing free radicals, in particular the superoxide anion and the hydroxyl radical; (3) selectively relaxing smooth muscle fibers; and (4) in vitro and in vivo keratinocyte growth, hair growth in humans, and fresh and accelerated fur growth in animals.
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- Efficient syntheses of pyrofolic acid and pteroyl azide, reagents for the production of carboxyl-differentiated derivatives of folic acid
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Reaction of folic acid (1) with excess trifluoroacetic anhydride provides access to both the previously unknown N10-(trifluoroacetyl)pyrrofolic acid (8) and pyrofolic acid (9). Reaction of either of these materials with hydrazine selectively affords pteroyl hydrazide (13), which may be oxidized to pteroyl azide (27) on a large scale (62% overall from I without the need for chromatography). Treatment of 27 with differentially protected glutamates provides a convenient and high-yielding synthesis of differentially protected, optically pure folates.
- Luo, Jin,Smith, Michael D.,Lantrip, Douglas A.,Wang, Susan,Fuchs
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p. 10004 - 10013
(2007/10/03)
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- New method of synthesis of D,L-5-oxoproline
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A new method for synthesis of D,L-5-oxoproline from N-acetyl-L-glutamic acid in weakly acid medium in the presence of water, and hydrolysis of an acetyl group and cyclization and total racemization of the acid simultaneously take place.The advantage of the method is the possibility of obtaining two individual amino acids with high yields in one chemical process using L-glutamic acid.
- Ermakova, G. A.,Skachilovw, S. Ya.,Yurchenko, N. I.
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- Amino acid of cycloaliphatic alcohols, process for their preparation and use as drugs
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Amino acid esters of cycloaliphatic alcohols of the formula: STR1 wherein A is cyclohexyl, cyclohexenyl, cyclopentyl and cyclopentenyl, substituted with from one to three radicals which are methyl, ethyl, and/or ethenyl. These amino acid esters have hypolipemic properties.
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- Novel spergualin-related compounds and compositions
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The present invention relates to novel spergualin-related compounds represented by the general formula [I]: STR1 wherein X is --(CH2)1?5 or STR2 Y is a hydrogen atom or a residue obtained by removing a hydroxyl group from the carboxyl group of an amino acid or a peptide; m is 0, 1 or 2 and n is 1 or 2, with the proviso that Y is not a hydrogen atom when n is 2 and m is 0. This compounds are stable and exhibit a high immunosuppressive activity.
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- THE SYNTHESIS AND CHARACTERIZATION OF 2,3-METHANOPYROGLUTAMIC ACID
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Details of the synthesis of 2,3-methanopyroglutamic acid (1), its N-methylamide (7) and N-β-naphthylamide (6) are reported.An NMR study of the conformation of 7 is discussed and the stability of the amide 6 to pyroglutamylaminopeptidase is detailed.The crystal structure of an alkene (4) formed during the pyrolysis of an intermediate pyrazoline (2) indicates that the (Z)-configuration is conserved during nitrogen extrusion.
- Mapelli, Claudio,Elrod, Luther F.,Holt, Elizabeth M.,Stammer, Charles H.
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p. 4377 - 4382
(2007/10/02)
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- Reactivite du nitrite de sodium. V. Action sur les amino-acides, peptides et proteines
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The action of sodium nitrite on various amino-acids was re-examined in conditions approximating to a biological medium. 13C-NMR provides evidence of the existence of intramolecular ring closures and the formation of 5-membered rings with ornithine, citrulline and arginine.The reaction of cystine shows the opening of the sulphur bridges, whereas cysteine leads to the formation of carboxy-thiiran and 3-sulpho-lactic acid.The hydrolysis of the amide bonds of asparagine and glutamine is complete whereas the peptides studied - carnosine and aspartam - do not undergo hydrolysis of the peptide linkage.However, the first deamination of glutathion (γ-Glu-Cys-Gly) induces the peptide link to be broken and a cyclization with the formation of lactone to occur.A second deamination takes place on the cysteinyl residue released and allows the formation of a thiiran by intramolecular cyclization with the thiol group.The formation of thiiran was also observed with oxidized glutathion which has an S-S bridge.Finally, the formation of nitrosamines was detected by 15N-NMR during the reaction of sodium nitrite with two commercial products available to the general public.
- Gouesnard, Jean-Paul
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- Thermal Syntheses of Polypeptides from N-Boc-Amino Acid(Aspartic Acid,β-Aminoglutaric Acid) Anhydrides
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N-t-Butyloxycarbonyl-amino acid(aspartic acid:Asp, glutamic acid:Glu, β-aminoglutaric acid: β-Agl)anhydrides were deprotected upon heating at temperatures slightly higher than the melting points of these compounds and polypeptides were synthesized easily in high yield.
- Munegumi, Toratane,Meng, Yan-Quing,Harada, Kaoru
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p. 1643 - 1646
(2007/10/02)
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- AGROPINE, A NEW AMINO ACID DERIVATIVE FROM CROWN GALL TUMOURS
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Agropine, an unusual compound produced in plant tumours was shown by mass spectrometry and proton and carbon-13 nmr spectroscopy to be a bicyclic derivative of glutamic acid and a hexitol sugar.
- Coxon, David T.,Davies, Anthony M. C.,Fenwick, G. Roger,Self, Ron,Firmin, John L.,et al.
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p. 495 - 498
(2007/10/02)
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- Process for the preparation of pyrrolidonecarboxylic acid/metal/amine complexes
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A process for the preparation of pyrrolidone-5-carboxylic acid/metal salt/amine complexes by reacting 1 mol of a L-glutamic acid lower alkyl ester/metal salt complex with 1 mol of an aliphatic, cycloaliphatic or aromatic-aliphatic damine or 2 mols of an aliphatic or cycloaliphatic monoamine in a polar solvent, with the elimination of 2 mols of alcohol. The complex compounds prepared according to the invention are valuable curing agents for epoxide resins.
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