Extended helical conformation newly observed in protein folding.

A new secondary structure, which shows regularity within the experimental error, is noticed in alpha-chymotrypsin, and considering its extended nature, the name epsilon-helix has been suggested for the same. The average observed values of phi and psi for this conformation are -93 degrees and +146 degrees, respectively. The helical parameters turn out to be n = 2.7 and h = 3.3 angstroms.