These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Beta-alanine containing cyclic peptides with turned structure: the "pseudo type II beta-turn." VI.
    Author: Pavone V, Lombardi A, Saviano M, Nastri F, Fattorusso R, Maglio O, Isernia C, Paolillo L, Pedone C.
    Journal: Biopolymers; 1994 Nov; 34(11):1517-26. PubMed ID: 7827263.
    Abstract:
    In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and nmr solution characterization, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(L-Pro-L-Phe-beta-Ala)2. The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylene chloride solution using N,N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P2(1) from methanol-dichloromethane solution. The two identical halves of the molecule adopt in the solid state two different conformations. One beta-Ala-L-Pro peptide bond is trans, while the second is cis. The molecule is present in dimethylsulfoxide d6 solutions as a mixture of conformational families. One of these corresponds to a C2 symmetrical molecule with both beta-Ala-Pro cis peptide bonds, while the second major conformation is very similar to that observed in the solid state. All Pro-Phe segments, both in the solid state and the symmetrical and unsymmetrical solution conformations, display phi, psi angles close to that of position i + 1 and i + 2 of type II beta-turns. In addition, the segments preceded by a trans beta-Ala-Pro peptide bond are characterized by a typical i<--i + 3 hydrogen bond, which is absent in the conformer containing a cis beta-Ala-Pro peptide bond. The latter conformation corresponds to a new structural domain we define as the "pseudo type II beta-turn."
    [Abstract] [Full Text] [Related] [New Search]