1.2 The backbone conformation of a peptide can be defined by two sets of rotation angles 1.2.1 The rotation angles around the n-ca bonds are labeled as phi(o), and around ca-c bonds are psi (y) 1.2.2 By convention, both phi and psi are defined aso degree in the conformation when the two peptide planes connected to the same a carbon are in the same plane. 1.2.3 In principle, phi and psi can have any value between-180 and +180 degrees. 1.2. 4 The conformation of the main chain is completely defined when phi and psi are specified for each residue in the chain1.2 The backbone conformation of a peptide can be defined by two sets of rotation angles. 1.2.1 The rotation angles around the N-Ca bonds are labeled as phi (), and around Ca-C bonds are psi (). 1.2.2 By convention, both phi and psi are defined as 0 degree in the conformation when the two peptide planes connected to the same a carbon are in the same plane. 1.2.3 In principle, phi and psi can have any value between -180 and +180 degrees. 1.2.4 The conformation of the main chain is completely defined when phi and psi are specified for each residue in the chain