ScrewFrame is a geometrical model for protein secondary-structure analysis based on the positions of the Cα atoms. Two implementations of ScrewFrame are available:
An earlier version of the same idea is the ScrewFit method. It differs from ScrewFrame in using the peptide planes rather than the Frenet frames attached to the Cα atoms for defining the screw motions. The newer ScrewFrame method performs as well but requires less input data, so we recommend using it instead.