Fig. 4. The geometric description of the succinimide formation.

a The Bürgi-Dunitz distance d (Å), N_Gly-C^γ_Asn and the angle θ (°), N_Gly-C^γ_Asn-O^δ_Asn are two variables describing the intramolecular conformational changes associated with the backbone-side chain conformational restructuring, required for succinimide ring closure. b In a polar coordinate system, both the waterless and the water assisted IRC paths are plotted, as calculated at the B3LYP/6-31+G(d,p) level of theory.