BIOACTIVE PEPTIDES - SOLID-STATE, SOLUTION AND MOLECULAR-DYNAMICS STUDIES OF A CYCLOLINOPEPTIDE-A RELATED CYSTINYL CYCLOPENTAPEPTIDE(322 visite) Rossi F, Saviano M, Di Blasio B, Zanotti G, Maione AM, Tancredi T, Pedone C
Parole chiave: Alcohol, Cyclolinopeptide A, Cyclopeptide, Cysteine, Disulfide, Pentapeptide, Solvent, Urethan, Article, Circular Dichroism, Crystal Structure, Hydrogen Bond, Infrared Spectroscopy, Molecular Dynamics, Nuclear Magnetic Resonance, Protein Conformation, Stereochemistry, Structure Activity Relation, X Ray Diffraction, Amino Acid Sequence, Molecular Sequence Data, Oligopeptides, Solutions, Support, Non-U.S. Gov, Thermodynamics, Non-U. S. Gov,
CSB del CNR, CIRPEB, Universita di Napoli, via Mezzocannone 4, 80134 Napoli, Italy
The conformational analysis of [GRAPHICS] the disulphide cyclopeptide-related cyclolinopeptide A, has been carried out by solid state methods using x-ray diffraction techniques, in solution by nmr, CD, ir spectroscopies, and by molecular dynamics (MD) analysis. The structure of the monoclinic form, obtained from ethanol (a = 11.303(2) Angstrom, b = 14.467(8) Angstrom, c = 12.355(2) Angstrom, beta(degrees) = 109.40(1), space group P2(1), Z = 2) presents two transannular H bonds with the formation of one type VIa beta-turn involving the C=O of the urethane moiety and the Phe(3) NH, and an intramolecular H bond between the C=O of urethane group and the Phe(4) NH. In the solid state all the peptide bonds are in the trans configuration with the exception of a cis peptide bond occurring between the Cys(1) and Pro(2) residues; the linkage S-S assumes right-handed chirality. The conformational study in solution by nmr spectroscopy indicates that the peptide is very flexible and that some conformer families are present at room temperature both in polar and apolar solvents. CD studies confirm that this cyclic system tends to give rise to a complex mixture of quasi-isoenergetic conformations, favored by the flexibility of the disulphide bridge and by the isomerism of the Xxx-Pro bond. MD studies carried out in vacuo and in solution shows that the structure determined by solid state represents a energy minimum. All hydrogen bonds found in the crystalline state are correctly reproduced in vacuo and in solution simulations. (C) 1994 John Wiley & Sons,Inc.
524 Records (511 escludendo Abstract e Conferenze). Impact factor totale: 2011.964 (1961.951 escludendo Abstract e Conferenze). Impact factor a 5 anni totale: 2050.614 (1996.772 escludendo Abstract e Conferenze).