Huy N Hoang, Russell W Driver, Renée L Beyer, Timothy A Hill, Aline D de Araujo, Fabien Plisson, Rosemary S Harrison, Lena Goedecke, Nicholas E Shepherd, David P Fairlie
Cyclic pentapeptides (e.g. Ac-(cyclo-1,5)-[KAXAD]-NH2 ; X=Ala, 1; Arg, 2) in water adopt one α-helical turn defined by three hydrogen bonds. NMR structure analysis reveals a slight distortion from α-helicity at the C-terminal aspartate caused by torsional restraints imposed by the K(i)-D(i+4) lactam bridge. To investigate this effect on helix nucleation, the more water-soluble 2 was appended to N-, C-, or both termini of a palindromic peptide ARAARAARA (≤5 % helicity), resulting in 67, 92, or 100 % relative α-helicity, as calculated from CD spectra...
July 11, 2016: Angewandte Chemie