Evidence for the 3(10)-helical structure of peptides based on antAib, a fluorophoric, anthracene-fused, 1-aminocyclopentane-1-carbocylic acid

Peptides based on 2-amino-2,3-dihydro-1H-cyclopenta[b]anthracene-2-carboxylic acid (antAib), a fluorescent, achiral, α-amino acid belonging to the class of C→C cyclized, Cα,α-disubstituted glycines, combined with L-Ala, up to the hexamer level, were synthesized by solution methods and chemically characterized. A conformational analysis by FTIR absorption and NMR techniques suggests that the highest oligomers of this series tend to fold into β-turns/310-helices. The UV absorption, CD, and fluorescence properties of these antAib/L-Ala model peptides are also described.