beta_turn_type_six_a beta_turn_type_six_a_two beta turn type six a two SO:0001153 A type VIa beta turn with the following phi and psi sngles on amino acid residues 2 and 3: phi-2 = -120 degrees, psi-2 = 120 degrees, phi-3 = -60 degrees, psi-3 = 0 degrees. type VIa2 turn type VIa2 beta turn sequence