ScrewFrame

ScrewFrame is a geometrical model for protein secondary-structure analysis based on the positions of the Cα atoms. Two implementations of ScrewFrame are available:

• The ScrewFrame Web server performs a ScrewFrame analysis on a single protein structure uploaded as a PDB file
• The ScrewFrame ActivePaper contains all the code and data from the original ScrewFrame publication and can be reused via the ActivePapers framework.

Reference:

• G. R. Kneller and K. Hinsen
  Protein secondary-structure description with a coarse-grained model
  Acta Cryst. D71, 1411–1422 (2015)
  (a preprint is available on arXiv)

ScrewFit

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.

References:

• G.R. Kneller and P. Calligari
  Efficient characterization of protein secondary structure in terms of screw motions
  Acta Cryst. D62, 302–311 (2006)

• P. Calligari and G.R Kneller
  ScrewFit: combining localization and description of protein secondary structure
  Acta Cryst. D68, 1690–1693 (2012)