Conformational studies of hexapeptides containing two dehydroamino acid residues in positions 2 and 5 in peptide chain

Abstract

Conformational preferences of a group of hexapeptides containing two dehydroamino acid residues in Positions 2 and 5 in peptide chain were investigated by means of spectroscopic methods (NMR and CD) and theoretical calculations. In the case of dimethylsulfoxide (DMSO) solution, only peptide with free N-termini adopted rigid 3(10)-helical conformation, for the rest of examined peptides extended and "zig-zag" conformers were predominant. CD measurements showed that only in chloroform solution the conformational freedom of investigated peptides was restricted.

Conformation of dehydropentapeptides containing four achiral amino acid residues – controlling the role of L-valine

“…Such a high flexibility was previously observed for peptides containing Δaa-Gly-Gly-Δaa sequences [41]. …”

Influence of solvents on conformation of dehydropeptides

“…Usually, analysis of the CD spectra of dehydropeptides are carried out in the near-UV region since, as shown our previous research [12,19,20], at shorter than 220 nm wavelengths there are overlapping contributions of the peptide, aromatic, and unsaturated chromophores which makes the band assignment and thus conformational analysis quite difficult. In the near-UV region, Cotton effects associated with the DPhe side chain is observed.…”

“…Previous studies indicate, that the influence of D-amino acid residue on peptide conformation depends on several factors. The most crucial is number of D-amino acid residues introduced into the peptide chain [4][5][6][7] as well as size of substituent on the C b atom of both: dehydroamino acid residue [8][9][10][11] and neighboring amino acid residue [6,[12][13][14][15][16][17][18][19][20]. Apart from these factors listed before, specific for the dehydropeptide, also other parameters, specific for the environment, have a strong influence on spatial conformation of the peptide chain.…”

Handedness preference and switching of peptide helices. Part II: Helices based on noncodedα‐amino acids

“…Privileged solution conformations of Δ Z Phe‐based peptides were satisfactorily determined by NMR analysis . Short peptides containing Δ Z Phe residues were generally shown to fold into conformations that may be perturbed by the H‐bonding capabilities of the solvent.…”

“…Induced CD proved to be an excellent tool to determine the solution conformation of peptides based on the achiral ΔPhe residue, especially in detecting the screw sense of the helices formed. It is principally for this reason that the number of publications on this topic is huge . The Δ Z Phe‐containing peptides show different CD curves in the near‐UV region depending on the main‐chain length and on the position in the sequence and number of the Δ Z Phe residues.…”