Structure cristalline de dérivés d'acides aminés. IV. Le composé d'addition LiBr.glycylglycylglycine

Meulemans, R.; Piret, Pierre; Meerssche, M. Van

doi:10.1107/s0567740871003728

Cited by 25 publications

(14 citation statements)

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“…Typically dipeptides participate in tridentate chelation by the N-terminal AA residue, through the NH 2 , N À1 , OCO À -fragments, as was obtained in Cu II and Pt II complexes [114][115][116][117][118]. These binding sites were fused in five-and six-membered chelate rings (figures 5 and 6).…”

Section: Characterization By Single-crystal X-ray Diffractionmentioning

confidence: 97%

“…The protonation of the peptide led to a shift of corresponding amide vibrations The new band at 1749 cm À1 corresponds to the C¼O of the -COOH fragment. The data for the higher Gly-analogs revealed that the values for NH are typical of trans-amide fragments where the frequency of the IR band corresponding to NH is observed within the range of 1560-1530 cm À1 (table 1) [116][117][118][119][120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135]. However, the strong overlapping of the spectroscopic patterns requires the application of other physical methods, such as NMR and MS.…”

Section: Introductionmentioning

confidence: 98%

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Protonation and coordination ability of small peptides – theoretical and experimental approaches for elucidation

Lamshöft

Ivanova

2011

Journal of Coordination Chemistry

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This review deals with modern theoretical and experimental approaches as well as structural elucidation of small peptides (SP), their protonated forms and metal complexes. Free peptide bond rotation in amino acids (AA) and peptides yielded various conformers, which may possess differing biological activities. Inter-and/or intramolecular stacking observed in aromatic SP is another phenomenon typical for both peptide salts and complexes. These phenomenological effects can be successfully studied, both theoretically and experimentally, using a combination of the theoretical approximations and physical methods, such as electronic absorption spectroscopy, vibrational spectroscopy (including IR and Raman), nuclear magnetic resonance, mass spectrometry, as well as single-crystal X-ray diffraction. The physical and chemical properties of these systems can be precisely calculated by ab initio and DFT methods, varying basis sets and the results obtained allow elucidation of their conformations as a function of the reaction conditions (pH, type of the solvent, temperature, metal to ligand molar ratio). Although the 3-D structures of many peptides have been determined over the past decades, peptide crystallization is still a major obstacle to crystallographic work and the presence of chiral center/s adds further difficulties. For this reason, a specific part of the review is focused on the study of the absolute structure of the peptides, their salts and metal complexes, discussing the conformational preferences of the peptides during these processes. The available crystallographic data for metal complexes are successfully used for the correlation between the structures and the spectroscopic properties.

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Section: Characterization By Single-crystal X-ray Diffractionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Protonation and coordination ability of small peptides – theoretical and experimental approaches for elucidation

Lamshöft

Ivanova

2011

Journal of Coordination Chemistry

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“…23 of [I] and in [7] [8]. ") In the LiBr complex of +H,N-Gly-Gly-Gly-O-, the NH3+ and COO-groups form a channel-like arrangement, with the Li+ ions tetrahedrally surrounded by three carboxylate and one amide 0-atom, and the Br-ions 'stuffed' in between near the glycine moieties in the middle of the tripeptide [16]. In addition to such specific interactions between amidesI8) or peptides and alkali/alkdline-earth ions, there are numerous other effects which come to mind in connection with our discovery.…”

Section: )mentioning

confidence: 99%

Solubilization of Peptides in Non‐polar Organic Solvents by the Addition of Inorganic Salts: Facts and Implications

Seebàch¹,

Thaler²,

Beck

1989

Helvetica Chimica Acta

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The solubility of open‐chain peptide derivatives (12 examples) in non‐polar, ether‐type organic solvents may be greatly increased by addition of salts (LiCl, LiBr, LiI, LiBF4, LiClO4, NaI, MgBr2 CaBr2, ZnCl2) or of titanates (Ti(OEt)4, Ti(OCHMe2)4). Examples are reported (Tables 2–6) in which this solubilizing effect leads to peptide concentrations more than one‐hundred‐fold those in the absence of salt (cf, BocAlaGlyGlyGlyOH in THF from 2g·1−1 to ≥ 300 g·1−1 with 6 equiv. of LiCl), 1H‐NMR Spectra of one of these solutions are reported (Fig. 1). There are no indications for epimerizations of stereogenic centres on the peptide backbone. Possible applications of these solutions in peptide chemistry are discussed.

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“…Of the two extreme geometries with dihedral angles Li-O=C-N 180" and 0", the former one appears to occur preferentially [23] [24] (see @ in Formula A of Scheme 2)'). There are chelate-type complexes with ten-membered rings as indicated in B [25].…”

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confidence: 98%

Calorimetric Measurements of the Complexation of Cyclosporin A, Ascomycin, Fujimycin, and Rapamycin with Lithium Chloride and with an Immunophilin

Seebàch

Bossler

Flowers

et al. 1994

Helvetica Chimica Acta

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(1 2.VII. 93) Solutions (2 ml) of small linear and cyclic peptides (411), of a peptolide containing nine amino acids and a lactate moiety (12), of the cyclic undecapeptide cyclosporin A (CS, l), and of the macrolides ascomycin, fujimycin, and rapamycin (1S-15) in THF were added to excess LiCI, LiBr, or LiCIO, (up to 3000 equiv. in 40 ml THF) in a calorimeter (calorimetric titration). The enthalpies of interaction measured are in the range of AH = -8 to -37 kcal/mol. A similar experiment was carried out with one of the binding proteins of cyclosporin, the human cyclophilin A, to give the thermodynamic parameters for the complexation AHo = -16, AG" = -10 kcal/mol, and AS' = -20 cal/mol .deg. at 25' which corresponds to an equilibrium constant K = 2. lo7 l/mol, in good agreement with the result of independent measurements using different methods. NMR Measurements of the macrolides in (D8)THF containing LiCl show strong down-field shifts of signals of the H-atoms next to C=O and C-OH groups in these molecules.

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Structure cristalline de dérivés d'acides aminés. IV. Le composé d'addition LiBr.glycylglycylglycine

Cited by 25 publications

References 0 publications

Protonation and coordination ability of small peptides – theoretical and experimental approaches for elucidation

Protonation and coordination ability of small peptides – theoretical and experimental approaches for elucidation

Solubilization of Peptides in Non‐polar Organic Solvents by the Addition of Inorganic Salts: Facts and Implications

Calorimetric Measurements of the Complexation of Cyclosporin A, Ascomycin, Fujimycin, and Rapamycin with Lithium Chloride and with an Immunophilin

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