Helix simulates the alpha-helix/random-coli transition in the secondary structures of peptides and proteins using a two-state matrix algorithm based upon the Lifson-Roig model. For a complete description of Helix, see Andersen and Tong, Protein Science, 6, 1997, p. 9870.
The CSDb attempts to simplify the calculation and comparison of chemical shift deviations (CSDs). The database accepts referenced chemical shift values for the alpha and/or amide protons of a peptide or protein sequence and, using sample and experiment-temperature information, calculates CSDs. Once entered, CSD data for different sequences, samples, and temperatures may be rapidly compared in graphical form.