- Preparation and characterization of a new open-tubular capillary column for enantioseparation by capillary electrochromatography
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In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9(34). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5?μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77?mmol·m?2. The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.
- Li, Yingjie,Tang, Yimin,Qin, Shili,Li, Xue,Dai, Qiang,Gao, Lidi
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p. 283 - 292
(2019/02/05)
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- Chromatographic Resolution of α-Amino Acids by (R)-(3,3'-Halogen Substituted-1,1'-binaphthyl)-20-crown-6 Stationary Phase in HPLC
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Three new chiral stationary phases (CSPs) for high-performance liquid chromatography were prepared from R-(3,3'-halogen substituted-1,1'-binaphthyl)-20-crown-6 (halogen = Cl, Br and I). The experimental results showed that R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 (CSP-1) possesses more prominent enantioselectivity than the two other halogen-substituted crown ether derivatives. All twenty-one α-amino acids have different degrees of separation on R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6-based CSP-1 at room temperature. The enantioselectivity of CSP-1 is also better than those of some commercial R-(1,1'-binaphthyl)-20-crown-6 derivatives. Both the separation factors (α) and the resolution (Rs) are better than those of commercial crown ether-based CSPs [CROWNPAK CR(+) from Daicel] under the same conditions for asparagine, threonine, proline, arginine, serine, histidine and valine, which cannot be separated by commercial CR(+). This study proves the commercial usefulness of the R-(3,3'-dibromo-1,1'-binaphthyl)-20-crown-6 chiral stationary phase.
- Wu, Peng,Wu, Yuping,Zhang, Junhui,Lu, Zhenyu,Zhang, Mei,Chen, Xuexian,Yuan, Liming
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supporting information
p. 1037 - 1042
(2017/07/25)
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- An easy 'Filter-and-Separate' method for enantioselective separation and chiral sensing of substrates using a biomimetic homochiral polymer
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We present a polyfluorene appended with protected l-glutamic acid that exhibited a reversible α-helix/β-sheet-like conformation and helical porous fibrous morphology mimicking the super-structure of proteins. The new homochiral polymer probe enabled efficient heterogeneous enantioselective separation and chiral sensing of a wide variety of substrates from their aqueous racemic mixture using an easy 'Filter-and-Separate' method.
- Senthilkumar,Asha
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supporting information
p. 8931 - 8934
(2015/05/27)
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- SEPARATING AGENT AND MANUFACTURING METHOD THEREOF
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An embodiment of the present invention is a separating agent wherein a group represented by a chemical formula of: or a group represented by a chemical formula of: is introduced on a surface thereof.
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Paragraph 0067; 0068; 0069; 0070; 0071; 0072; 0073; 0074
(2015/01/07)
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- Isolation and synthesis of falcitidin, a novel myxobacterial-derived acyltetrapeptide with activity against the malaria target falcipain-2
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A 384-well microtitre plate fluorescence cleavage assay was developed to identify inhibitors of the cysteine protease falcipain-2, an important antimalarial drug target. Bioassay-guided isolation of a MeOH extract from a myxobacterium Chitinophaga sp. Y23 isolated from soil collected in Singapore, led to the identification of a new acyltetrapeptide, falcitidin (1), which displayed an IC 50 value of 6 μM against falcipain-2. The planar structure of 1 was secured by NMR and MS/MS analysis. Attempts to isolate further material for biological testing were hampered by inconsistent production and by a low yield (100 μg l -1). The absolute configuration of 1 was determined by Marfey's analysis and the structure was confirmed through total synthesis as isovaleric acid-D-His-L-Ile-L-Val-L-Pro-NH 2. Falcitidin (1) is the first member of a new class of falcipain-2 inhibitors and, unlike other peptide-based inhibitors, does not contain reactive groups that irreversibly bind to active cysteine sites.
- Somanadhan, Brinda,Kotturi, Santosh R.,Yan Leong, Chung,Glover, Robert P.,Huang, Yicun,Flotow, Horst,Buss, Antony D.,Lear, Martin J.,Butler, Mark S.
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p. 259 - 264
(2013/07/27)
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- SEPARATING AGENT FOR CHROMATOGRAPHY
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A separating agent for chromatography is provided that is useful for the separation of specific compounds, e.g., for the optical resolution of amino acids. This separating agent for chromatography provides a higher productivity and contains a crown ether-like cyclic structure and optically active binaphthyl. This separating agent for chromatography containing a crown ether-like cyclic structure and optically active binaphthyl is provided by introducing a substitution group for binding to carrier into a specific commercially available 1,1′-binaphthyl derivative that has substituents at the 2, 2′, 3, and 3′ positions, then introducing a crown ether-like cyclic structure, and subsequently chemically bonding the binaphthyl derivative to the carrier through the substitution group for binding to carrier.
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Paragraph 0074; 0075
(2013/08/15)
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- Aminolytic reaction catalyzed by d-stereospecific amidohydrolases from Streptomyces spp
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From investigation of 2000 soil isolates, we identified two serine-type amidohydrolases that can hydrolyze d-aminoacyl derivatives from the culture supernatant of Streptomyces species 82F2 and 83D12. The enzymes, redesignated as 82F2-DAP and 83D12-DAP, were purified for homogeneity and characterized. Each enzyme had molecular mass of approximately 40 kDa, and each showed moderate stability with respect to temperature and pH. Among hydrolytic activities toward d-aminoacyl-pNAs, the enzymes showed strict specificity toward d-Phe-pNA, but showed broad specificity toward d-aminoacyl esters. The specific activity for d-Phe-pNA hydrolysis of 82F2-DAP was ten-fold higher than that of 83D12-DAP. As a second function, each enzyme showed peptide bond formation activity by its function of aminolysis reaction. Based on results of d-Phe-d-Phe synthesis under various conditions, we propose a reaction mechanism for d-Phe-d-Phe production. Furthermore, the enzymes exhibited peptide elongation activity, producing oligo homopeptide in a one-pot reaction. We cloned the genes encoding each enzyme, which revealed that the primary structure of each enzyme showed 30-60% identity with those of peptidases belonging to the clan SE, S12 peptidase family categorized as serine peptidase with d-stereospecificity.
- Arima, Jiro,Ito, Hitomi,Hatanaka, Tadashi,Mori, Nobuhiro
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experimental part
p. 1460 - 1469
(2012/01/12)
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- Chiral separation of underivatized amino acids by reactive extraction with palladium-BINAP complexes
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(Figure Presented) In answer to the need for a more economic technology for the separation of racemates, a novel system for reactive enantioselective liquid-liquid extraction (ELLE) is introduced. Palladium (S)-BINAP complexes are employed as hosts in the separation of underivatized amino acids. The system shows the highest selectivity for the ELLE of tryptophan with metal complexes as hosts reported to date and shows a good selectivity toward a range of natural and unnatural amino acids. Furthermore, the host can be prepared in situ from commerically available compounds. Bulk-membrane transport in the form of U-tube experiments demonstrates the enantioselective and catalytic nature of the transport. The dependency of the system on parameters such as pH, organic solvent, and host-substrate ratio has been established. 31P NMR spectroscopy has been used to confirm the preferred enantiomer in the extraction experiments. The intrinsic selectivity was deduced by determination of the association constants of the palladium complex with the tryptophan enantiomers.
- Verkuijl, Bastiaan J. V.,Minnaard, Adriaan J.,De Vries, Johannes G.,Feringa, Ben L.
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experimental part
p. 6526 - 6533
(2010/03/01)
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- Amino acid ionic liquids as chiral ligands in ligand-exchange chiral separations
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Recently, amino acid ionic liquids (AAILs) have attracted much research interest. In this paper, we present the first application of AAILs in chiral separation based on the chiral ligand exchange principle. By using 1alkyl-3-methylimidazolium L-proline (L-Pro) as a chiral ligand coordinated with copper(II), four pairs of underivatized amino acid enantiomers - DLphenylalanine (DL-Phe), DL-histidine (DL-His), DL-tryptophane (DL-Trp), and DL-tyrosine (DL-Tyr) - were successfully separated in two major chiral separation techniques, HPLC and capillary electrophoresis (CE), with higher enantioselectivity than conventionally used amino acid ligands (resolution (Rs) = 3.26-10.81 for HPLC; Rs = 1.34-4.27 for CE). Interestingly, increasing the alkyl chain length of the AAIL cation remarkably enhanced the enantioselectivity. It was inferred that the alkylmethylimidazolium cations and L-Pro form ion pairs on the surface of the sta-tionary phase or on the inner surface of the capillary. The ternary copper complexes with L-Pro are consequently attached to the support surface, thus inducing an ion-exchange type of retention for the DL-enantiomers. Therefore, the AAIL cation plays an essential role in the separation. This work demonstrates that AAILs are good alternatives to conventional amino acid ligands for ligand-exchange-based chiral separation. It also reveals the tremendous application potential of this new type of task-specific ILs.
- Liu, Qian,Wu, Kangkang,Tang, Fei,Yao, Lihua,Yang, Fei,Nie, Zhou,Yao, Shouzhuo
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body text
p. 9889 - 9896
(2010/04/06)
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- Amine-boranes: Effective reducing agents for the deracemisation of DL-amino acids using L-amino acid oxidase from Proteus myxofaciens
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The deracemisation of DL-α-amino acids using L-amino acid oxidase from Proteus myxofaciens and amine-boranes as chemical reducing agents has been investigated. Amine-boranes were found to be of particular interest in terms of reactivity and chemoselectivity compared to sodium borohydride and cyanoborohydride. Starting from the racemate, a range of D-amino acids were obtained in yields of up to 90% and e.e. >99%.
- Alexandre, Fran?ois-René,Pantaleone, David P.,Taylor, Paul P.,Fotheringham, Ian G.,Ager, David J.,Turner, Nicholas J.
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p. 707 - 710
(2007/10/03)
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- Compounds for and methods of inhibiting matrix metalloproteinases
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The present invention relates to compounds of Formula I that inhibit matrix metalloproteinases and to a method of inhibiting matrix metalloproteinases using the compounds More particularly, the present invention relates to a method of treating diseases in which matrix metalloproteinases are involved such as multiple sclerosis, atherosclerotic plaque rupture, restenosis, aortic aneurysm, heart failure, periodontal disease, corneal ulceration, burns, decubital ulcers, chronic ulcers or wounds, cancer metastasis, tumor angiogenesis, osteoporosis, rheumatoid or osteoarthritis, renal disease, left ventricular dilatation, or other autoimmune or inflammatory diseases dependent upon tissue invasion by leukocytes.
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- Preparation of D-histidine and derivatives thereof from L-histidine
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D-histidine and its derivatives are manufactured from L-histidine, by mixing L-histidine and tartaric acid with an aldehyde in acetic acid medium and thereafter precipitating D-histidine tartrate from the reaction mass. Pure D-histidine can then be recovered from the crude D-histidine tartrate.
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- The use of histidine decarboxylase for the isolation of D-histidine from the racemate
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A procedure has been developed for the straightforward isolation of enantiomerically pure D-histidine from the racemate by action of histide decarboxylase (EC. 4.1.1.22) on racemic histidine followed by crystallization.The histamine formed has been isolated as its dipicrate from the mother liquor.
- Foppen, Marie-Anne E.,Rantwijk, Fred van,Maat, Leendert,Kieboom, Antonius P. G.
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p. 424 - 425
(2007/10/02)
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- Method of making a diastereomeric mixture containing two diastereomeric N-acyl-amino acid esters
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In the process of hydrocarboxylating an α-enamide with CO and an organic hydroxyl compound to produce a N-acyl-α-amino acid ester, the improvement comprising using as the organic hydroxyl compound reactant, an organic hydroxyl compound which has a chiral center that is essentially all L or D, thereby producing a reaction mixture having essentially no enantiomeric pairs and containing diastereomeric N-acyl-α-amino acid esters having two chiral centers.
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- Method of making a diastereomeric mixture containing two diastereomeric N-acyl-amino acid esters
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In the process of hydrocarboxylating an α-enamide with CO and an organic hydroxyl compound to produce a N-acyl-α-amino acid ester, the improvement comprising using as the organic hydroxyl compound reactant, an organic hydroxyl compound which has a chiral center that is essentially all L or D, thereby producing a reaction mixture having essentially no enantiomeric pairs and containing diastereomeric N-acyl-α-amino acid esters having two chiral centers.
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- Total Asymmetric Transformations at Interfaces with Centrosymmetric Cristals: Role of Hydrophobic and Kinetic Effects in the Crystallization of the System Glycine/α-Amino Acids
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A model of generation and amplification of optical activity, using the centrosymmetric crystals of glycine as substrates for total separation of occluded α-amino acids into enantiomeric territories, is described.The principle is based on the enantioselective occlusion of these additives through the enantiotopic (010) and (00) faces of glycine cristals.Such crystals, when floating at the air/solution interface, and if correctly oriented, may incorporate only one of the two enantiomeric additives present in solution.We demonstrate that complete (010) or (00) orientation may be induced by both kinetic and "hydrophobic" effects.The former is achieved through inhibition of nucleation and growth of the say (010) oriented crystals , by (S) amino acids in solution, while the latter is due to induction of (00) orientation by (S) hydrophobic amino acids.By symmetry the enantiomers induce opposite orientation.The two effects are investigated separately, and possible mechanisms are proposed.Combimation of the two effects, which operate in the same direction, allows total orientation of glycin crystals and thus triggering of amplification starting with a solution containing leucine with an enantiomeric excess as low as 6percent.The relevance of such a mechanism to other systems and to nucleation in general is discussed.
- Weissbuch, I.,Addadi, L.,Leiserowitz, L.,Lahav, M.
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p. 561 - 567
(2007/10/02)
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- Optimal Conditions for the Enzymatic Production of D-Amino Acids from the Corresponding 5-Substituted Hydantoins
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The reaction conditions for the production of D-p-hydroxyphenylglycine (D-HPG) from DL-5-(p-hydroxyphenyl)hydantoin (DL-HPH) by cells of Pseudomonas sp.AJ-11220 and the cultural conditions for this bacterium for the formation of the D-HPG-producing enzyme involved by this bacterium were investigated.The optimal pH of this reaction was about 8.0 and the optimal temperature about 43 deg C.The D-HPG producing enzyme was inducibly produced in Pseudomonas sp.AJ-11220 in proportion to the cell growth.Cells containing high activity were obtained when Pseudomonas sp.AJ-11220 was grown in a medium containing 20 g of glucose 5 g of (NH4)2SO4, 1g of KH2PO4, 3 g of K2HPO4, 0.5 g of MgSO4.7H2O, 0.01 g of FeSO4.7H2O, 0.01 g of MnSO4.4H2O, 10 g of yeast extract 5 g of DL-5-cyanoethylhydantoin and 20 g of CaCO3 in a total volume of 1 liter (pH 7.0).Under the optimal conditions, 25 mg/ml of D-HPG was asymmetrically and directly produced from 30 mg/ml of DL-HPH with a molar yield of 92percent.Various D-amino acids could also be effectively produced from the corresponding 5-substituted hydantoins.
- Yokozeki, Kenzo,Nakamori, Shigeru,Yamanaka, Shigeru,Eguchi, Chikahiko,Mitsugi, Koji,Yoshinaga, Fumihiro
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p. 715 - 720
(2007/10/02)
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