title: Understanding the role of stereoelectronic effects in determining collagen stability. 2. A quantum mechanical/molecular mechanical study of (Proline-Proline-Glycine)(n) polypeptides.
abstract: The importance of vicinal and long-range interresidue effects in determining the stability of the collagen triple helix has been investigated by quantum mechanical (QM) and molecular mechanical (MM) computations on suitable model polypeptides, taking into account solvent effects by the polarizable continuum model (PCM). At the QM level, the PII conformation corresponds to an energy minimum for pentapeptide analogues incorporating the sequence Gly-Pro-Pro-Gly, irrespective of the down or up puckering of the pyrrolidine ring. However, our computations indicate that the alternation of down and up prolines characterizing collagen and collagen-like peptides is not due to an intrinsic preference of the Pro-Pro-Gly sequence. This result is confirmed by MM computations of longer polypeptides. Next, MM computations on model triple helices show that a better packing is obtained for specific values of backbone dihedrals, which, in turn, favor the alternation of down and up prolines along each chain.
authors.affiliation: Dipartimento di Chimica, Università Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Naples, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Improta
authors.forename: Franca
authors.initials: F
authors.lastname: Mele
authors.forename: Orlando
authors.initials: O
authors.lastname: Crescenzi
authors.forename: Caterina
authors.initials: C
authors.lastname: Benzi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
mesh_terms: D003094:Collagen / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D009842:Oligopeptides; C044555:prolyl-prolyl-glycine; D003094:Collagen