Conformational study of poly‐ΔAbu peptides and construction of amphipathic nanostructure

Abstract

Generally, it is believed that alpha,beta-dehydroamino acid residues are most stable in the Z- form rather than in the E- form. In this study, it has been shown that poly-DeltaAbu exists in alternate Delta(E)Abu and Delta(Z)Abu form, with phi, psi values of approximately 0 degrees , 80 degrees and 35 degrees , 27 degrees for the E- and Z- forms, respectively, rather than the all Z- form. The conformational results for the peptides Ac-DeltaAbu(2)-NHMe and Ac-L/D-Ile-Delta(Z)Abu/Delta(E)Abu-NHMe suggest the incorporation of DeltaAbu in both the Z- and E- forms, which is consistent with the available observations in natural systems. Because of adoption of phi, psi values corresponding to the collagen type structure ( approximately -30 degrees , 120 degrees ) by Ile residue and with phi, psi values in the left-handed helical region for Delta(Z)Abu residue, the peptide Ac-(L-Ile-Delta(Z)Abu)(3)-NHMe adopts an amphipathic left-handed helical beta-sheet type structure. This structure is stabilized by network of hydrogen bonding, carbonyl-carbonyl, and CH-O interactions and can be exploited for the construction of antimicrobial peptides and nanomaterials.

The synthesis of dehydrotryptophan and dehydrotryptophan-containing peptides

“…a,b-Dehydroamino acids are non-proteinogenic residues often found in natural products produced by microorganisms, marine organisms and plants. 1 Dehydroamino acids usually exist as the Z-isomer as it is thermodynamically more stable than the Eisomer. [1][2][3][4] The E-and Z-isomers of certain dehydroamino acids, such as dehydrophenylalanine and dehydrotryptophan, are able to interconvert photochemically, either when incorporated into peptides or as part of smaller derivatives.…”

“…1 Dehydroamino acids usually exist as the Z-isomer as it is thermodynamically more stable than the Eisomer. [1][2][3][4] The E-and Z-isomers of certain dehydroamino acids, such as dehydrophenylalanine and dehydrotryptophan, are able to interconvert photochemically, either when incorporated into peptides or as part of smaller derivatives. 4, 5 The E/Z configuration of the double bond affects the conformation of dehydroamino acid containing peptides, and hence the biological activity of these compounds.…”

Effect of the ΔPhe residue configuration on a didehydropeptides conformation: A combined CD and NMR study

“…It has been shown recently, though, that poly-∆Abu exists in alternate ∆ Z Abu and ∆ E Abu form rather than the all Zform. 1 A great majority of papers published so far on dehydropeptides deal with ∆-amino acid residues of the Z configuration. The most studied dehydroamino acid residue has been dehydrophenylalanine.…”