- Structure and conformation of the tripeptide: N-t-Boc-Prolyl-Phenylalanyl-Proline (Boc-Pro-Phe-Pro)
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The structure and conformation of the tripeptide N-t-Boc-Prolyl-Phenylalanyl-Proline (Boc-Pro-Phe-Pro) (C24H33N3O6) have been investigated with X-ray crystallographic and spectroscopic methods.Two conformations of Boc-Pro-Phe-Pro crystallized in the space
- Milne, P. J.,Oliver, D. W.,Roos, H. M.
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- Development of a practical solid-phase synthesis approach to 1,3,5-triazepan-2,6-diones
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1,3,5-Triazepan-2,6-diones are a class of conformationally restricted heterocycles derived from dipeptides. With the aim to develop a general and practical method useful for library production, three polymer-assisted syntheses, all based on a catch and release approach, have been evaluated and compared. The method involving a Hofmann rearrangement of N-Boc dipeptide carboxamides and subsequent trapping of the isocyanate on polymer-supported N-hydroxysuccinimide (PS-HOSu) was found to be the most reliable and versatile, allowing rapid access to the 1,3,5-triazepan-2,6-dione skeleton.
- Boeglin, Joel,Venin, Claire,Guichard, Gilles
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experimental part
p. 7472 - 7478
(2012/09/22)
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- NOVEL THIAZINE OR PYRAZINE DERIVATIVES
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An object of the present invention is to synthesize novel compounds having 3-oxo-3, 4-dihydro-2H-1, 4-thiazine or 2-oxo-1, 2, 3, 4-tetrahydropyrazine as a main skeleton. The present invention relates to compounds represented by the following general formula [I] and salts thereof. In the formula, X is S or R6-(A2)n-N, R1 and R2 are H, alkyl, cycloalkyl or aryl, R3 and R4 are H, alkyl, cycloalkyl, aryl or aromatic heterocycles, R5 is H, alkyl, cycloalkyl, aryl or -A3-A4-R7, R6 is H, alkyl, cycloalkyl, OH, alkoxy, aryl, aryloxy or an aromatic heterocycle, R7 is H, alkyl, OH, alkoxy, aryl, aryloxy, amino, alkylamino, arylamino, an aromatic heterocycle or a nonaromatic heterocycle, A1 is alkylene, A2 is carbonyl or sulfonyl, A3 is alkylene, and A4 is carbonyl or oxalyl.
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- Conformational Studies in Solid State and Solution of Protected C-terminal Dipeptide Fragment (Boc-Phe-Pro-NH2) of Morphiceptin
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The crystal structure of the protected C-terminal dipeptide fragment (Boc-Phe-Pro-NH2) of the μ-opioid receptor highly selective agonist, morphiceptin (Tyr-Pro-Phe-Pro-NH2), was determined; the crystals are monoclinic with space group P21 and unit cell dimensions: α = 11.5731(5), b = 6.4490(3), c = 15.4082(5) A, β = 100.359(5)° and Z = 2. To examine the influence of proline on the conformation of peptide bond, the molecular conformation was studied in solid state and solution (using 1H and 13C NMR data). The X-ray analysis revealed the following conformations of peptide backbone: φ1 = -63.2(5)°, ψ1 = 156.1(4)°, ω1 = -174.3(4)°, φ2 = -66.0(5)° and ψ2 = 152.0(4)°. The conformation of the Boc group is trans-trans. Experimental data revealed the trans conformation about the Phe-Pro amide bond, both in solid state and solution (DMSO). The possibility of cis/trans isomerization about the peptide bond (ω1) was examined by theoretical calculations using BIOSYM software. Molecular modelling, including molecular dynamics simulations of the title dipeptide, is in favour of trans peptide bond.
- Kojic-Prodic, Biserka,Antolic, Snjezana,Kveder, Marina,Zigrovic, Ivanka,Kidric, Jurka,Horvat, Stefica
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p. 259 - 277
(2007/10/03)
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- Synthesis and biological activity of branched enkephalin analogues
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The synthesis and biological activity of a new type of enkephalin analogs are reported. A series of branched pentapeptides of the enkephalin sequence with replacement of 2-glycine by D-ornithine and branching of the peptide chain in position 2 by attachment of proline, leucine, asparagine or methionine residues to the 8-amino group of D-ornithine were synthesized by classical solution methodology. Analgesic activity of the new analogs was assayed by the 'tail pinch' method following intracisternal and intravenous administrations to mice. They showed higher analgesic potency and longer duration of action as compared to linear and cyclic pentapeptides with the same amino acid composition. The activity determined in the GPI and MVD bioassays, and in a binding assay, revealed the preference of the branched analogs for the μ-type of opioid receptor over the δ-type. These results raise the possibility to synthesize enkephalin analogs with high analgesic potency and opiate receptor selectivity by varying the chemical character and length of the side chain in the 2-position.
- Bobrova, Irina,Abissova, Natalia,Mishlakova, Natalia,Rozentals, Guntis,Chipens, Gunar
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p. 255 - 266
(2007/10/03)
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- Synthesis of Thyrotropin-Releasing Hormone Analogues. 1. Complete Dissociation of Central Nervous Effects from Thyrotropin-Releasing Activity
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Twenty-four thyrotropin-releasing hormone (TRH) analogues containing mainly aliphatic amino acids in position 2 were synthesized and tested for central nervous system (CNS) and hormonal (TSH) activity.Application of the pentafluorophenyl ester method in t
- Szirtes, Tamas,Kisfaludy, Lajos,Palosi, Eva,Szporny, Laszlo
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p. 741 - 745
(2007/10/02)
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