Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation

Chih-Chang Hung; Atsushi Yabushita; Takayoshi Kobayashi; Pei-Feng Chen; Keng S Liang

doi:10.1016/j.bpc.2016.05.001

Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation

Biophys Chem. 2016 Jul-Aug:214-215:11-6. doi: 10.1016/j.bpc.2016.05.001. Epub 2016 May 10.

Authors

Chih-Chang Hung¹, Atsushi Yabushita², Takayoshi Kobayashi³, Pei-Feng Chen⁴, Keng S Liang⁵

Affiliations

¹ Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
² 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.
³ 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.
⁴ Institute of Physics, Academia Sinica, Taipei, Taiwan.
⁵ Institute of Physics, Academia Sinica, Taipei, Taiwan; Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan.

PMID: 27183248
DOI: 10.1016/j.bpc.2016.05.001

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.

Keywords: Ligand rebinding; Nitric oxide synthase; Photo-dissociation; Ultrafast spectroscopy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Arginine / chemistry*
Cell Line
Energy Transfer
Heme
Humans
Imidazoles / chemistry*
Kinetics
Ligands
Nitric Oxide Synthase Type III / chemistry*
Protein Binding
Spectrum Analysis / methods*
Substrate Specificity
Thermodynamics*
Vibration

Substances

Imidazoles
Ligands
Heme
imidazole
Arginine
Nitric Oxide Synthase Type III