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Banerjee R, Sheet T. Ratio of ellipticities between 192 and 208 nm (R 1 ): An effective electronic circular dichroism parameter for characterization of the helical components of proteins and peptides. Proteins 2017; 85:1975-1982. [PMID: 28707342 DOI: 10.1002/prot.25351] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/09/2017] [Accepted: 07/10/2017] [Indexed: 01/28/2023]
Abstract
Circular dichroism (CD) spectroscopy represents an important tool for characterization of the peptide and protein secondary structures that mainly arise from the conformational disposition of the peptide backbone in solution. In 1991 Manning and Woody proposed that, in addition to the signal intensity, the ratio between [θ]nπ* and [θ]ππ*ǁ ((R2 ) ≅ [θ]222 /[θ]208 ), along with [θ]ππ*⊥ and [θ]ππ*ǁ ((R1 ) ≅ [θ]192 /[θ]208 ), may be utilized towards identifying the peptide/protein conformation (especially 310 - and α-helices). However, till date the use of the ratiometric ellipticity component for helical structure analysis of peptides and proteins has not been reported. We studied a series of temperature dependent CD spectra of a thermally stable, model helical peptide and its related analogs in water as a function of added 2,2,2-trifluoroethanol (TFE) in order to explore their landscape of helicity. For the first time, we have experimentally shown here that the R1 parameter can characterize better the individual helices, while the other parameter R2 and the signal intensity do not always converge. We emphasize the use of the R1 ratio of ellipticities for helical characterization because of the common origin of these two bands (exciton splitting of the amide π→ π* transition in a helical polypeptide). This approach may become worthwhile and timely with the increasing accessibility of CD synchrotron sources.
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Affiliation(s)
- Raja Banerjee
- Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology), Salt Lake, Kolkata, 700064, West Bengal, India
| | - Tridip Sheet
- Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology), Salt Lake, Kolkata, 700064, West Bengal, India
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2
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Bertolani A, Pizzi A, Pirrie L, Gazzera L, Morra G, Meli M, Colombo G, Genoni A, Cavallo G, Terraneo G, Metrangolo P. Crystal Structure of the DFNKF Segment of Human Calcitonin Unveils Aromatic Interactions between Phenylalanines. Chemistry 2017; 23:2051-2058. [PMID: 27806188 PMCID: PMC5573999 DOI: 10.1002/chem.201604639] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Indexed: 12/24/2022]
Abstract
Although intensively studied, the high-resolution crystal structure of the peptide DFNKF, the core-segment of human calcitonin, has never been described. Here we report how the use of iodination as a strategy to promote crystallisation and facilitate phase determination, allowed us to solve, for the first time, the single-crystal X-ray structure of a DFNKF derivative. Computational studies suggest that both the iodinated and the wild-type peptides populate very similar conformations. Furthermore, the conformer found in the solid-state structure is one of the most populated in solution, making the crystal structure a reliable model for the peptide in solution. The crystal structure of DFNKF(I) confirms the overall features of the amyloid cross-β spine and highlights how aromatic-aromatic interactions are important structural factors in the self-assembly of this peptide. A detailed analysis of such interactions is reported.
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Affiliation(s)
- Arianna Bertolani
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Andrea Pizzi
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Lisa Pirrie
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Lara Gazzera
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Giulia Morra
- Istituto di Chimica del Riconoscimento MolecolareCNRVia Mario Bianco 920131MilanoItaly
| | - Massimiliano Meli
- Istituto di Chimica del Riconoscimento MolecolareCNRVia Mario Bianco 920131MilanoItaly
| | - Giorgio Colombo
- Istituto di Chimica del Riconoscimento MolecolareCNRVia Mario Bianco 920131MilanoItaly
| | - Alessandro Genoni
- Laboratoire SRSMC, UMR 7565CNRSVandoeuvre-lès-Nancy54506France
- Laboratoire SRSMC, UMR 7565Université de LorraineVandoeuvre-lès-Nancy54506France
| | - Gabriella Cavallo
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Giancarlo Terraneo
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
| | - Pierangelo Metrangolo
- Laboratory of Nanostructured Fluorinated Materials (NFMLab)Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”Politecnico di MilanoVia L. Mancinelli 720131MilanoItaly
- Istituto di Chimica del Riconoscimento MolecolareCNRVia Mario Bianco 920131MilanoItaly
- HYBER Centre of ExcellenceDepartment of Applied PhysicsAalto University, P.O. Box 1510002150EspooFinland
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St-Cyr DJ, García-Ramos Y, Doan ND, Lubell WD. Aminolactam, N-Aminoimidazolone, and N-Aminoimdazolidinone Peptide Mimics. TOPICS IN HETEROCYCLIC CHEMISTRY 2017. [DOI: 10.1007/7081_2017_204] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Abstract
The ‘CαNN’ motif has an intrinsic affinity for the anions and can recognize anion through local interactions along with augmentation of the helical conformation at the motif segment.
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Affiliation(s)
- Tridip Sheet
- Maulana Abul Kalam Azad University of Technology (Formerly Known as West Bengal University of Technology)
- Kolkata – 700064
- India
| | - Raja Banerjee
- Maulana Abul Kalam Azad University of Technology (Formerly Known as West Bengal University of Technology)
- Kolkata – 700064
- India
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5
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Kajihara Y, Tanabe Y, Sasaoka S, Okamoto R. Homogeneous Human Complex-Type Oligosaccharides in Correctly Folded Intact Glycoproteins: Evaluation of Oligosaccharide Influence On Protein Folding, Stability, and Conformational Properties. Chemistry 2012; 18:5944-53. [DOI: 10.1002/chem.201103428] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Indexed: 11/06/2022]
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6
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Grauer AA, Cabrele C, Zabel M, König B. Stable right- and left-handed peptide helices containing C(alpha)-tetrasubstituted alpha-amino acids. J Org Chem 2009; 74:3718-26. [PMID: 19354242 DOI: 10.1021/jo900222g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Short peptidomimetics with stable secondary structures in solution are of interest for applications in chemistry, biology, and medicine. One way to rigidify the backbone of a peptide is the use of cyclic C(alpha)-tetrasubstituted alpha-amino acids (TAAs) like compound 14. The structures resulting from the incorporation of this unnatural amino acid into peptides were investigated. In total, 13 different peptides with a length of up to eight residues and alternating sequences of TAA 14 and (S)- or (R)-valine were synthesized. Their structures were characterized by X-ray diffraction analysis and NMR and CD measurements showing that the all-S-backbone-configured peptides 5 and 6 (SS)(2-3) form right-handed 3(10)-helices, while the all-R-configured peptides 11-13 (RR)(2-4) form left-handed 3(10)-helices in the solid state and solution.
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Affiliation(s)
- Andreas A Grauer
- Institute for Organic Chemistry, University of Regensburg, D-93040 Regensburg, Germany
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7
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Banerjee R, Chattopadhyay S, Basu G. Conformational preferences of a short Aib/Ala-based water-soluble peptide as a function of temperature. Proteins 2009; 76:184-200. [PMID: 19137603 DOI: 10.1002/prot.22337] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The amino acid Aib predisposes a peptide to be helical with context-dependent preference for either 3(10)- or alpha- or a mixed helical conformation. Short peptides also show an inherent tendency to be unfolded. To characterize helical and unfolded states adopted by water-soluble Aib-containing peptides, the conformational preference of Ac-Ala-Aib-Ala-Lys-Ala-Aib-Lys-Ala-Lys-Ala-Aib-Tyr-NH(2) was determined by CD, NMR and MD simulations as a function of temperature. Temperature-dependent CD data indicated the contribution of two major components, each an admixture of helical and extended/polyproline II structures. Both right- and left-handed helical conformations were detected from deconvolution of CD data and (13)C NMR experiments. The presence of a helical backbone, more pronounced at the N-terminal, and a temperature-induced shift in alpha-helix/3(10)-helix equilibrium, more pronounced at the C-terminal, emerged from NMR data. Starting from polyproline II, the N-terminal of the peptide folded into a helical backbone in MD simulations within 5 ns at 60 degrees C. Longer simulations showed a mixed-helical backbone to be stable over the entire peptide at 5 degrees C while at 60 degrees C the mixed-helix was either stable at the N-terminus or occurred in short stretches through out the peptide, along with a significant population of polyproline II. Our results point towards conformational heterogeneity of water-soluble Aib-based peptide helices and the associated subtleties. The problem of analyzing CD and NMR data of both left- and right-handed helices are discussed, especially the validity of the ellipticity ratio [theta](222)/[theta](207), as a reporter of alpha-/3(10)- population ratio, in right- and left-handed helical mixtures.
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Affiliation(s)
- Raja Banerjee
- Department of Biotechnology, West Bengal University of Technology, Kolkata 700064, India.
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8
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Scott WL, Alsina J, Audu CO, Babaev E, Cook L, Dage JL, Goodwin LA, Martynow JG, Matosiuk D, Royo M, Smith JG, Strong AT, Wickizer K, Woerly EM, Zhou Z, O'Donnell MJ. Distributed Drug Discovery, Part 2: global rehearsal of alkylating agents for the synthesis of resin-bound unnatural amino acids and virtual D(3) catalog construction. ACTA ACUST UNITED AC 2009; 11:14-33. [PMID: 19105725 PMCID: PMC2651687 DOI: 10.1021/cc800184v] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Distributed Drug Discovery (D3) proposes solving large drug discovery problems by breaking them into smaller units for processing at multiple sites. A key component of the synthetic and computational stages of D3 is the global rehearsal of prospective reagents and their subsequent use in the creation of virtual catalogs of molecules accessible by simple, inexpensive combinatorial chemistry. The first section of this article documents the feasibility of the synthetic component of Distributed Drug Discovery. Twenty-four alkylating agents were rehearsed in the United States, Poland, Russia, and Spain, for their utility in the synthesis of resin-bound unnatural amino acids 1, key intermediates in many combinatorial chemistry procedures. This global reagent rehearsal, coupled to virtual library generation, increases the likelihood that any member of that virtual library can be made. It facilitates the realistic integration of worldwide virtual D3 catalog computational analysis with synthesis. The second part of this article describes the creation of the first virtual D3 catalog. It reports the enumeration of 24 416 acylated unnatural amino acids 5, assembled from lists of either rehearsed or well-precedented alkylating and acylating reagents, and describes how the resulting catalog can be freely accessed, searched, and downloaded by the scientific community.
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Affiliation(s)
- William L Scott
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University, Indianapolis, Indiana 46202-3274, USA.
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9
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Miyashita M, Mizutani T, Tadano G, Iwata Y, Miyazawa M, Tanino K. Pd-Catalyzed Stereospecific Azide Substitution of α,β-Unsaturated γ,δ-Epoxy Esters with Double Inversion of Configuration. Angew Chem Int Ed Engl 2005; 44:5094-7. [PMID: 16021641 DOI: 10.1002/anie.200500838] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Masaaki Miyashita
- Division of Chemistry, Graduate School of Science, Hokkaido University, 060-0810 Sapporo, Japan.
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Miyashita M, Mizutani T, Tadano G, Iwata Y, Miyazawa M, Tanino K. Pd-Catalyzed Stereospecific Azide Substitution of α,β-Unsaturated γ,δ-Epoxy Esters with Double Inversion of Configuration. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200500838] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Synthesis of α,α-disubstituted 4-phosphonophenylalanine analogues as conformationally-constrained phosphotyrosyl mimetics. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Highly diastereoselective synthesis of new, carbostyril-based type of conformationally-constrained β-phenylserines. Tetrahedron 2003. [DOI: 10.1016/s0040-4020(03)01172-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Toniolo C, Crisma M, Formaggio F, Peggion C. Control of peptide conformation by the Thorpe-Ingold effect (C alpha-tetrasubstitution). Biopolymers 2002; 60:396-419. [PMID: 12209474 DOI: 10.1002/1097-0282(2001)60:6<396::aid-bip10184>3.0.co;2-7] [Citation(s) in RCA: 580] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The preferred conformations of peptides heavily based on the currently extensively exploited achiral and chiral alpha-amino acids with a quaternary alpha-carbon atom, as determined by conformational energy computations, crystal-state (x-ray diffraction) analyses, and solution ((1)H-NMR and spectroscopic) investigations, are reviewed. It is concluded that 3(10)/alpha-helical structures and the fully extended (C(5)) conformation are preferentially adopted by peptide sequences characterized by this family of amino acids, depending upon overall bulkiness and nature (e.g., whether acyclic or C(alpha) (i) <--> C(alpha) (i) cyclized) of their side chains. The intriguing relationship between alpha-carbon chirality and bend/helix handedness is also illustrated. gamma-Bends and semiextended conformations are rarely observed. Formation of beta-sheet structures is prevented.
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Affiliation(s)
- C Toniolo
- Department of Organic Chemistry, University of Padova, Institute of Biomolecular Chemistry, CNR, 35131 Padova, Italy.
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14
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Banerjee R, Basu G. Direct evidence for alteration of unfolding profile of a helical peptide by far-ultraviolet circular dichroism aromatic side-chain contribution. FEBS Lett 2002; 523:152-6. [PMID: 12123823 DOI: 10.1016/s0014-5793(02)02974-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Aromatic side-chains are known to contribute to the far-UV circular dichroism (CD) spectra of peptides and proteins. Among other things, this can significantly affect the measured helix propensities of amino acids [Chakrabartty et al., Biochemistry 32 (1993) 5560-5565]. In order to address how interfering side-chain contributions can affect the backbone unfolding transition of a helical peptide, as monitored by [theta;](222) (molar ellipticity at 222 nm), we have studied the unfolding transition of a short designed (alpha-amino isobutyric acid/alanine-based) helical peptide containing an interacting Tyr residue. The guanidinium hydrochloride-induced unfolding of the peptide, as monitored by [theta;](222), showed the presence of a sharp transition superposed over a much broader transition. When the same experiment was performed with a similar peptide that lacked the interacting Tyr residue, the sharp transition disappeared and only the broad transition remained. The sharp transition was assigned to originate from the interacting Tyr side-chain. This demonstrates that conformationally restricted aromatic side-chains that interact with the helical backbone not only can alter the backbone far-UV CD signal, they may also alter the unfolding profiles, monitored by far-UV CD, rendering them unfit for a simple analysis for extracting the appropriate unfolding thermodynamic parameters.
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Affiliation(s)
- Raja Banerjee
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, 700 054, Calcutta, India
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15
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Stalker RA, Munsch TE, Tran JD, Nie X, Warmuth R, Beatty A, Aakeröy CB. Asymmetric synthesis of two new conformationally constrained lysine derivatives. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00450-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Warmuth R, Munsch TE, Stalker RA, Li B, Beatty A. Enantioselective synthesis of benzocyclic α,α-dialkyl-amino acids: new insight into the solvent dependent stereoselectivity of the TMSCN addition to phenylglycinol derived imines. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(01)00505-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Olajos E, Peter A, Casimir R, Tourwe D. HPLC enantioseparation of phenylalanine analogs by application of (S)-N-(4-nitrophenoxycarbonyl)phenylalanine methoxyethyl ester as a new chiral derivatizing agent. Chromatographia 2001. [DOI: 10.1007/bf02491837] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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18
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Péter A, Olajos E, Casimir R, Tourwé D, Broxterman QB, Kaptein B, Armstrong DW. High-performance liquid chromatographic separation of the enantiomers of unusual alpha-amino acid analogues. J Chromatogr A 2000; 871:105-13. [PMID: 10735291 DOI: 10.1016/s0021-9673(99)00889-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The direct and indirect stereochemical resolution of the enantiomers of ring- and alpha-methyl-substituted phenylalanines and phenylalanine amides was attempted by high-performance liquid chromatographic methods. The direct separation was carried out on two chiral stationary phases, the crown-ether-based Crownpak CR(+), and the teicoplanin-based Chirobiotic T, while the indirect resolution was performed by applying pre-column derivatization with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC) and Nalpha-(2,4-dinitro-5-fluorophenyl)-L-alanine amide (Marfey's reagent, FDAA). The Chirobiotic T column was efficient in the separation of ring- and alpha-methyl-substituted phenylalanine analogues, but was ineffective for the amides of these analogues. The Crownpak CR(+) column separated the ring-substituted phenylalanines and amides, whereas the alpha-methylated analogues were coeluted. Of the two indirect methods, GITC derivatization seemed more effective than FDAA derivatization.
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Affiliation(s)
- A Péter
- Department of Inorganic and Analytical Chemistry, Attila József University, Szeged, Hungary.
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