Fig. 3.

a) improper angle τ and torsion angle ω for substrate at ES, TI1 and TI2 states. Improper angle τ: N′-C-H′-CA′ is employed to indicate the inversion of leaving N, while torsion angle ω: CA-C-N′-CA′ is defined to control the rotation of NH group around the scissile bond. b) Superposition of structures of active site region for ES (in red), TI1 (in green), TI2 (in blue) and EA1 (in orange) in stick mode. The HG atom of Ser195 is also presented in sphere mode.