β-alanine containing cyclic peptides with turned structure: The 'pseudo type II β-turn. ' VI(179 visite) Pavone V, Lombardi A, Saviano M, Nastri F, Fattorusso R, Maglio O, Isernia C, Paolillo L, Pedone C
Parole chiave: Beta Alanine, Cyclopeptide, Article, Chemical Bond, Molecular Dynamics, Peptide Synthesis, Protein Conformation, Protein Purification, Protein Structure, Proton Nuclear Magnetic Resonance, X Ray Crystallography, Amino Acid Sequence, Beta-Alanine, Molecular Sequence Data, Secondary, Support, Non-U.S. Gov, Non-U. S. Gov,
CIRPB/CEINGE-Biotecnol. Avanzate, University of Naples Federico II, Via Mezzocannone 4, 80134 Napoli, Italy
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-β-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 P21 from methanol-dichloro-methane solution. The two identical halves of the molecule adopt in the solid state two different conformations. One β-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 β-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 φ,ψ angles close to that of position i + 1 and i + 2 of type II β-turns. In addition, the segments preceeded by a trans β-Ala-Pro peptide bond are characterized by a typical i ← i + 3 hydrogen bond, which is absent in the conformer containing a cis β-Ala-Pro peptide bond. The latter conformation corresponds to a new structural domain we define as the 'pseudo type II β- turn.'
480 Records (465 escludendo Abstract e Conferenze). Impact factor totale: 1756.118 (1701.772 escludendo Abstract e Conferenze). Impact factor a 5 anni totale: 1861.607 (1804.881 escludendo Abstract e Conferenze).