Conformational Angles and Properties of andOmega;-Amino Acids in ProteinFolding

The conformational properties of β-amino acid residues are based on three degrees of freedom: φ (N Cβ), θ (Cβ Cα), ψ (Cα CO). Similarly, the conformational variabilities of γand δamino acid residues are defined as four [φ (N Cγ), θ1 (Cγ Cβ), θ2 (Cβ Cα), ψ (Cα CO)] and five [[φ (N Cδ), θ1 (Cδ Cγ), θ2 (Cγ Cβ), θ3 (Cβ Cα), ψ (Cα CO)] degrees of freedom, respectively [8]. Figure 1a illustrates the comparison of backbone torsion angles in α-, β-, γand δ-amino acid residues.