Evidence for the 3₁₀‐helical structure of peptides based on antAib, a fluorophoric, anthracene‐fused, 1‐aminocyclopentane‐1‐carboxylic acid

Abstract

Peptides based on 2-amino-2,3-dihydro-1H-cyclopenta[b]anthracene-2-carboxylic acid (antAib), a fluorescent, achiral, alpha-amino acid belonging to the class of C(i) (alpha)-->C(i) (alpha) cyclized, C(alpha,alpha)-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 beta-turns/3(10)-helices. The UV absorption, CD, and fluorescence properties of these antAib/L-Ala model peptides are also described.

Recent progress on the stereoselective synthesis of cyclic quaternary α-amino acids

“…Apart from these classical rings, the conformational tendencies of other cyclic amino acids such as Hms(Ipr) or O , O -isopropylidene-α-hydroxymethylserine,25 Afc or 9-amino-9-fluorenecarboxylic acid,26,27 Daf or 9-amino-4,5-diazafluorene-9-carboxylic acid,28,29 Adt 4-amino-1,2-dithiolane-4-carboxylic acid,30 the axially chiral α-amino acids Bip and Bin31–37 or the Bip system incorporating a crown ether receptor38 have been reported. More recently, the synthesis and properties of antAib, a novel tetrasubstituted α-amino acid of the Ac 5 c type possessing a fused anthracene fluorophore has also been reported 39,40…”