Browsing by Author "Chen, Pei-Feng"

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Envelope Structure of Human eNOS Protein Revealed by Small-Angle X-ray Scattering
(2012-04-01)
Chen, Chun-Yu
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Chen, Pei-Feng
;
Hwu, Yeukuang
;
Jeng, U-Ser
;
Wu, Kun-Yu
We investigate the solution structure of human eNOS protein by using synchrotron small-angle X-ray scattering (SAXS). The pair-correlation analysis of the profile shows the radius of gyration (R-g) and maxima dimension (D-max) of 6.87 +/- 0.03 nm and 22 nm, respectively. The ratio of D-max and R-g revealed that the protein was an extended conformation. The ab initio shape determination and rigid-body calculations were performed to reconstruct the real-space structure of eNOS in solution. The result shows that human eNOS form homodimer form in solution with the closed contact of two oxygenase domains.
Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation
(2016-07-08)
Hung, Chih-Chang
;
Yabushita, Atsushi
;
Kobayashi, Takayoshi
;
Chen, Pei-Feng
;
Liang, Keng S.
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 <300 fs, then followed by vibrational cooling and recombination within 2 ps. 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 400 fs, vibrational cooling, charge transfer, and complete ground-state recovery within 1.4 ps. The eNOS-oxy without additive is partially bound with water molecule, thus its photoexcited dynamics also shows ligand dissociation in <800 fs. Then it followed by vibrational cooling coupled with charge transfer in 4.8 ps, and recombination of ligand to distal side of heme in 12 ps. (C) 2016 Elsevier B.V. All rights reserved.
Ultrafast relaxation dynamics of nitric oxide synthase studied by visible broadband transient absorption spectroscopy
(2017-09-01)
Hung, Chih-Chang
;
Yabushita, Atsushi
;
Kobayashi, Takayoshi
;
Chen, Pei-Feng
;
Liang, Keng S.
Ultrafast dynamics of endothelial nitric oxide synthase (eNOS) oxygenase domain was studied by transient absorption spectroscopy pumping at Soret band. The broadband visible probe spectrum has visualized the relaxation dynamics from the Soret band to Q-band and charge transfer (CT) band. Supported by two-dimensional correlation spectroscopy, global fitting analysis has successfully concluded the relaxation dynamics from the Soret band to be (1) electronic transition to Q-band (0.16 ps), (2) ligand dissociation and CT (0.94 ps), (3) relaxation of the CT state (4.0 ps), and (4) ligand rebinding (59 ps). (C) 2017 Elsevier B.V. All rights reserved.