This program calculates the Dihedral (phi and psi) and the Angles(C-N-CA, N-CA-C, CA-C-N) of the main chain for the given protein.

Phi is the dihedral made by
  1. carboxylic carbon of the previous amino acid, C
  2. amide group nitrogen, N
  3. alpha carbon, CA
  4. carboxylic carbon, C
Psi is the dihedral made by
  1. amide group nitrogen, N
  2. alpha carbon, CA
  3. carboxylic carbon, C
  4. amide group nitrogen of the next amino acid, N
Determines dihedral and angles of each amino acids of main chain of Protein sequence
Dihedral Angles
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  3. Click on Submit.

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Phi and psi are the two torsional angles that determine the overall backbone conformation of a protein. G.N. Ramachandran used computer models of small polypeptides to systematically vary phi and psi with the objective of finding stable confirmations.

G.N. Ramachandran and V. Sasiskharan(1968) Adv. Protein Chem. 23, 283-437.
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