Key residues and processes. (1) FAD is reduced and Asp397 and Arg368 respond immediately. (2) Asn403 reacts similarly fast and undergoes a slow phase of response up to 20 ps. (3) A delayed (from 1 ps) and complex motion of water molecules is completed at 20 ps. (4) Met408 undergoes a photoreaction from 1 ps to 20 ps. (5) Trp381 is oxidized at 300 ps, with structural changes evolving around it up to 100 μs.
