13Cα and 13Cβ chemical shifts as a tool to delineate β-hairpin structures in peptides

Unravelling the factors that contribute to the formation and the stability of β-sheet structure in peptides is a subject of great current interest. A β-hairpin, the smallest β-sheet motif, consists of two antiparallel hydrogen-bonded β-strands linked by a loop region. We have performed a statistical analysis on protein β-hairpins showing that the most abundant types of β-hairpins, 2:2, 3:5 and 4:4, have characteristic patterns of 13Cα and 13Cβ conformational shifts, as expected on the basis of their φ and ψ angles. This fact strongly supports the potential value of 13Cα and 13Cβ conformational shifts as a means to identify β-hairpin motifs in peptides. Their usefulness was confirmed by analysing the patterns of 13Cα and 13Cβ conformational shifts in 13 short peptides, 10–15 residues long, that adopt β-hairpin structures in aqueous solution. Furthermore, we have investigated their potential as a method to quantify β-hairpin populations in peptides.