Parole chiave: Conformations, Hydrogen Bonds, Molecular Structure, Single Crystals, Synthesis (chemical), X Ray Analysis, Conformational Preferences, Cyclic Peptides, Intramolecular Hydrogen Bond, Proteins, Beta Alanine, Cyclopeptide, Pentapeptide, Article, Peptide Synthesis, Protein Conformation, X Ray Crystallography, Amino Acid Sequence, Beta-Alanine, Molecular Sequence Data,
CNR and CEINGE, Centro Interdipartimentale, University of Naples Federico II, via Mezzocannone 4, 80134 Napoli, Italy
In the present paper we describe the synthesis, purification, and single crystal x-ray analysis of the cyclic pentapeptide cyclo-(Pro-Phe-Phe-β-Ala- β-Ala). This compound crystallizes in the orthorhombic space group P212121 from methanol and adopts in the solid state an unusual conformation characterized by a cis β-Ala5-Pro1 peptide bond and by an intramolecular hydrogen bond stabilizing a C11- and a C12-ring structure. The C11 structure contains the Phe3 and the β-Ala4 at the corner position of the turn; it is the first observation of a type II β-turn enlargement due to the insertion of an extra methylene group of the β- alanine residue. The rest of the molecule participates in a newly characterized C12-ring structure, which incorporates a β-Ala residue at position i of the turn.
194 Records (192 escludendo Abstract e Conferenze). Impact factor totale: 763.61 (758.072 escludendo Abstract e Conferenze). Impact factor a 5 anni totale: 815.211 (809.496 escludendo Abstract e Conferenze).