title: Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation.
abstract: Ultrafast transient absorption spectroscopy of endothelial NOS oxygenase domain (eNOS-oxy) was performed to study dynamics of ligand or substrate interaction under Soret band excitation. Photo-excitation dissociates imidazole ligand in <300fs, then followed by vibrational cooling and recombination within 2ps. Such impulsive bond breaking and late rebinding generate proteinquakes, which relaxes in several tens of picoseconds. The photo excited dynamics of eNOS-oxy with L-arginine substrate mainly occurs at the local site of heme, including ultrafast internal conversion within 400fs, vibrational cooling, charge transfer, and complete ground-state recovery within 1.4ps. The eNOS-oxy without additive is partially bound with water molecule, thus its photoexcited dynamics also shows ligand dissociation in <800fs. Then it followed by vibrational cooling coupled with charge transfer in 4.8ps, and recombination of ligand to distal side of heme in 12ps.
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Chih-Chang
authors.initials: CC
authors.lastname: Hung
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan; Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Yokohama 221-8686, Japan; CREST, JST, Saitama, Japan. Electronic address: yabushita@mail.nctu.edu.tw.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yabushita
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan; Department of Applied Physics and Chemistry and Institute for Laser Science, The University of Electrocommunications, Tokyo, Japan; CREST, JST, Saitama, Japan; Institute of Laser Engineering, Osaka University.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Institute of Physics, Academia Sinica, Taipei, Taiwan.
authors.forename: Pei-Feng
authors.initials: PF
authors.lastname: Chen
authors.affiliation: Institute of Physics, Academia Sinica, Taipei, Taiwan; Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Keng S
authors.initials: KS
authors.lastname: Liang
mesh_terms: D001120:Arginine / Q000737:chemistry*; D002460:Cell Line; D004735:Energy Transfer; D006418:Heme; D006801:Humans; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D052250:Nitric Oxide Synthase Type III / Q000737:chemistry*; D011485:Protein Binding; D013057:Spectrum Analysis / Q000379:methods*; D013379:Substrate Specificity; D013816:Thermodynamics; D014732:Vibration
chemical_list: D007093:Imidazoles; D008024:Ligands; D006418:Heme; C029899:imidazole; D001120:Arginine; D052250:Nitric Oxide Synthase Type III
keywords: Ligand rebinding; Nitric oxide synthase; Photo-dissociation; Ultrafast spectroscopy