Professor Nien-Hui Ge and postdoctoral researcher Hiroaki Maekawa, in collaboration with the Toniolo group in Italy, recently reported in the Journal of the American Chemical Society how 2D IR spectra change as the number of residues in a polypeptide increases. The onset of 3₁₀-helical secondary structure appears to occur upon the formation of a complete 3₁₀-helical turn at the pentapeptide level. The work is an important step in establishing 2D IR spectrum–structure relationship and will provide a useful baseline for studying the helix-coil transition.