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Summary Methyl esters of the pentafluoropropionyl-amino acid derivatives of the tetrafunctional, sulphur-bridged, stereoisomeric lanthionines, cystathionines and -methyl-lanthionines were resolved on glass capillaries coated with the chiral stationary phase N-propionyl-L-valine-N-tert-butylamide-polysiloxane (Chirasil-Val) within 35min. Interestingly, L-cystathionine elutes before its D-enantiomer in contrast to the usual order of emergence on an L-phase. The method was applied to the polypeptide antibiotic nisin, which contains mesolanthionine and 2S,3S,6R-3-methyl-lanthionine.N-Pentafluoropropionyl-S-alkylthiocysteine methyl esters (R=methyl, ethyl, n- and iso-propyl, n- and sec-butyl, n-octyl, neo-pentyl, cyclohexyl-, benzyl-, tolyl-) were separated on Chirasil-Val within 30min. The identity of all derivatives was shown by combined gas chromatography-mass spectrometry. 相似文献
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Sulfonic acids have been shown to be more effective than the commonly used trifluoroacetic acid (TFA) in the chiral resolution of underivatized aromatic amino acids on an amylosic column. Sulfonic acid additives give a more UV transparent mobile phase, possibly allowing the detection of non-aromatic analytes. Work presented demonstrates that through the combination of sulfonic acid mobile phase additives, amine mobile phase additives and solvent modifier variations, the enantiomers of 20 of 25 probe amino acids are fully resolved, four are partially resolved with only one failing to be separated on a common amylosic column. 相似文献
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Summary N-Trifluoroacetyl (TFA) dipeptide-o-carboranyl propyl esters of L-valyl-L-valine and L--amino-n-butyryl-L--amino-n-butyric acid have been prepared and the properties of these two new stationary phases for the gas-liquid chromatographic sepaation of amino acid enantiomers have been examined. It was found that the amino acid derivatives have shorter retention times, while maintaining good separation factors, on these carborane phases as compared to other dipeptide stationary phases. Both high and low boiling derivatives have been resolved on a 165 m×0.5 mm capillary column. The new phases have greater thermal stability and can be utilized over a wide temperature range. 相似文献
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Yu. N. Belokon' V. I. Maleev T. F. Savel'eva N. S. Garbalinskaya M. B. Saporovskaya V. I. Bakhmutov V. M. Belikov 《Russian Chemical Bulletin》1989,38(3):557-561
Conclusions Asymmetric alkylation of the amino acid fragment of Ni2+ complexes of the Schiff bases of glycine with N-(2-pyridinecarbonyl)-o-aminobenzophenone and of alanine with N-(2-pyridinecarbonyl)-o-aminobenzaldehyde has been carried out under phase-transfer conditions using N-benzylcinchonidinium chloride as the chiral phase-transfer catalyst.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 631–635, March, 1989. 相似文献
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Enzymatic preparation of optically active silicon-containing amino acids and their application 总被引:2,自引:0,他引:2
Takuo Kawamoto Hayato Yamanaka Atsuo Tanaka 《Applied biochemistry and biotechnology》2000,88(1-3):17-22
Optically active 3-trimethyl silylalanine (TMS-Ala) was prepared by hydrolysis of N-acetyl-dl-TMS-Ala catalyzed by acylase I (aminoacylase; N-acylamino-acid amidohydrolase, EC3.5.1.14). Acylase I from porcine kidney (PKA) was found to be more effective than that
from Aspergillus melleus in the preparation of l-TMS-Ala. Under the optimized conditions, optically pure l-TMS-Ala (>99% enantiomeric excess, ee) was obtained with a 72% yield. Furthermore, a highly optically pure d-TMS-Ala (96% ee) could also be obtained with a 76% yield by chemical hydrolysis of the residual substrate. Enzymatic synthesis
of peptides containing TMS-Ala was also attempted in ethyl acetate. Benzyloxycarbonyl (Z)-l-TMS-Ala served as the substrate for thermolysin, whereas l-TMS-Ala-OMe was inactive as the amino component. In the case of inhibitory activity of dipeptides toward thermolysin, l-Leu-(l-TMS-Ala) was found to be a more potent inhibitor than l-Leu-l-Leu, which is known to be one of the most effective inhibitors of thermolysin among the dipeptides consisting of natural
aminoacids. 相似文献
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Synthesis and characterization of supramolecular optically active bisamides derived from amino acids
The synthesis and phase transitional behaviour of three pairs of enantiomeric supramolecular hexacatenar liquid crystals (LCs) derived from natural α-amino acids such as l/d-alanine, l/d-leucine and l/d-valine are described. Their preparation with high enantiomeric purity was accomplished by condensing optically active (amino acid residue containing) trialkoxy amines with a 3,4,5-trialkoxy cinnamic acid core using a peptide coupling reagent namely, 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate (HBTU). The mesomorphic behaviour of these self-complementing mesogens was ascertained by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction. The compounds exhibit columnar (Col) phase over a wide thermal range. Particularly, a pair of enantiomers derived from l/d-leucine residues notably stabilize hexagonal Col (Colh) phase over a wide temperature range of ?5 °C to 180 °C. Circular dichroism (CD) and FTIR studies suggest the chiral (helical) organization of mesogens within the columns through intermolecular hydrogen bonding; thus, these enantiomers represent one of the rarely reported examples of LCs exhibiting supramolecular Colh phase at room temperature. The gelation studies reveal the ability of these bisamides to form stable supramolecular gels in ethanol caused through H-bonding interactions. 相似文献
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Emiko Koyama Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(14):2925-2934
Polycondensations of dicarboxylic acids with diols having amide moieties derived from optically active amino alcohols were carried out. Polymers with M ns 8,700–17,400 were obtained by the polycondensations using 1.2 eq. of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) in DMF at room temperature for 8 h in satisfactory yields. The Tg of the polymer rose with decrease of the methylene chain length of the dicarboxylic acid. In the Tgs of the polymers from L-leucinol, even-odd effect was observed with increase of the methylene chain length of the dicarboxylic acid. The molecular rotation values of the polymers were constant except for the polymer from succinic acid, which showed the negatively largest one. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2925–2934, 1997 相似文献
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Tocainide and its 14 analogues were resolved on a chiral stationary phase (CSP) based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 covalently bonded to silica gel. The resolution was quite good, the separation (alpha) and resolution factors (Rs) being 1.84-15.32 and 1.34-13.78, respectively. Especially, the result for the resolution of tocainide on the CSP turns out to be the best one among others reported so far. The chromatographic resolution behaviors were demonstrated to be dependent on the content and the type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase. 相似文献
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