title: Conformational study of the neurotensin and substance P fragments: Pro-Arg-Arg-Pro and Arg-Pro-Lys-Pro.
abstract: The conformational behaviour of the basic hydrophilic Pro-Arg-Arg-Pro and Arg-Pro-Lys-Pro peptides, neurotensin (NT) and Substance P fragments, has been taken up by semi-empirical calculations. The presence of two Pro residues prevents these peptides from giving any folded structure (alpha helix, beta turn . . .). In both peptides the most stable conformations are essentially relative to more or less stretched structures; structures involving one or more residues in a gamma turn form are often encountered in Pro-Arg-Arg-Pro peptide while mixed structures involving residues in very different conformations are found for the Arg-Pro-Lys-Pro-peptide. In both peptides, positively charged Lys and Arg side-chains most often point in opposite directions. The Pro-Arg-Arg-Pro peptide is part of the active NT (7-13) fragment where both Arg residues are necessary to the activity. A tentative study shows that the hydrophilic tetrapeptide induces NT (7-13) stretched conformations.
mesh_terms: D000595:Amino Acid Sequence; D009496:Neurotensin; D009842:Oligopeptides; D010446:Peptide Fragments; D011392:Proline; D011487:Protein Conformation; D013373:Substance P
chemical_list: D009842:Oligopeptides; D010446:Peptide Fragments; D013373:Substance P; D009496:Neurotensin; D011392:Proline