DSSP - Define Secondary Structure of Proteins
|Author||Kabsch W, Sander C.|
DSSP performs a search for patterns in the resolved structure of a protein. Therefore it predicts H-Bonds by a cutoff in the energy bond. It searches for "n-turns" and bridges. "n-turns" are H-Bonds between the 0H of residue i and the NH of residue i+n (n = 3 or 4 or 5; 4 is the classical alpha-Helix), whereas bridges are H-Bonds not near each other in sequence (repeated bridges form beta-Sheets).
DSSP knowns different features and depending on the predicted features of an amino acid is the secondary structure assigned.
First it searches for H-Bonds by a cutoff in the energy bond. With the H-Bonds it searches for turns and bridges. These turns and bridges are used for the search of alpha-helices and beta-ladders. Geometrical features are bends, chirality, SS bonds and solvent exposure. With these features DSSP assigns the secondary structure (8 different states).