New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

Abstract

The preferred conformation of five, terminally protected, model peptide series to the hexamer level, based on three novel crowned, C(alpha)-methyl L-DOPA amino acids combined with either L-Ala/Aib or Gly/Aib, were assessed in structure supporting solvents using FT-IR absorption, (1)H NMR, and CD techniques. The FT-IR absorption spectra strongly suggest that the contribution of the crowned C(alpha)-tetrasubstituted residue to intramolecular H-bonding is equivalent to that of Aib and is much more significant than that of either L-Ala or Gly. In addition, the (1)H NMR titrations and the CD patterns resemble those typically exhibited by (right-handed) 3(10)-helical structures.

Synthesis, Ion Complexation Study, and 3D‐Structural Analysis of Peptides Based on Crown‐Carrier, Cα‐Methyl‐L‐DOPA Amino Acids

“…We do not attribute the limited sensitivity of the crown-carrier Mdp NH 2 chemical shift induced by the perturbing solvent to the participation of this NH group in the intramolecular H-bonding scheme of the folded hexapeptide, but rather to a substantial inaccessibility of the solvent promoted by the bulkiness and chemical characteristics of the ring-substituted Mdp side-chain and its position in the peptide sequence. [38] Taken together, our FTIR absorption and 1 H NMR results favor the conclusion that the longest oligomers of the seven Mdp-based peptide series tend to fold into well developed β-turns and 3 10 -helices (indeed in these ordered secondary structures neither the NH 1 nor the NH 2 group is expected to be involved in intramolecular H-bonds). [21] This outcome is not surprising in view of the well established α -methylated α-amino acids.…”

Towards sequence selective DNA binding: design, synthesis and DNA binding studies of novel bis-porphyrin peptidic nanostructures

“…The starting point for the design of a versatile peptidic scaffold was based on work previously reported, by our group 20 and others, 21 for the construction of engineerable peptidic frameworks. The general concept of this work was to use a-helical peptidic structures as scaffolds to orient multiple macrocyclic ligands on top of each other.…”

Structures and conformation of a benzo‐12‐crown‐4 containing dipeptide

“…Moreover crown ether side chain containing peptides exhibit ionophore like properties . These features have been exploited in chemical and biological research . Further, derivatives of crown ether containing peptides have shown their potential to induce apoptosis, suggesting that some functionalized crown molecules could be used in cancer therapy …”

“…5 These features have been exploited in chemical and biological research. [6][7][8][9][10][11][12][13][14][15][16][17][18] Further, derivatives of crown ether containing peptides have shown their potential to induce apoptosis, suggesting that some functionalized crown molecules could be used in cancer therapy. 19 Several Research groups have synthesized crown containing L-DOPA (L23,4-dihydroxyphenylalanine) derivatives as a receptor for metal ions.…”

“…19 Several Research groups have synthesized crown containing L-DOPA (L23,4-dihydroxyphenylalanine) derivatives as a receptor for metal ions. [6][7][8][9][10][11][12][13][14][15][16][17][18] Till date, structural characterization of a crown ring containing peptide has eluded determination in the solid state. The crystallization of the crown containing peptides is fraught with difficulties possibly due to the availability of a large number of almost isoenergetic conformers of the crown ring.…”