Effect of conformational states on protein dynamical transition.
In order to examine the properties specific to the folded protein, the effect of the conformational states on protein dynamical transition was studied by incoherent elastic neutron scattering for both wild type and a deletion mutant of staphylococcal nuclease. The deletion mutant of SNase which lacks C-terminal 13 residues takes a compact denatured structure, and can be regarded as a model of intrinsic unstructured protein. Incoherent elastic neutron scattering experiments were carried out at various temperature between 10 K and 300 K on IN10 and IN13 installed at ILL. Temperature dependence of mean-square displacements was obtained by the q-dependence of elastic scattering intensity. The measurements were performed on dried and hydrated powder samples. No significant differences were observed between wild type and the mutant for the hydrated samples, while significant differences were observed for the dried samples. A dynamical transition at approximately 140 K observed for both dried and hydrated samples. The slopes of the temperature dependence of MSD before transition and after transition are different between wild type and the mutant, indicating the folding induces hardening. The hydration water activates a further transition at approximately 240 K. The behavior of the temperature dependence of MSD is indistinguishable for wild type and the mutant, indicating that hydration water dynamics dominate the dynamical properties.
Nakagawa
Hiroshi
H
Neutron Biophysics Group, Neutron Biology Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan.
Kamikubo
Hironari
H
Kataoka
Mikio
M
D002942:Circular Dichroism; D008836:Micrococcal Nuclease / Q000737:chemistry*; D009502:Neutrons; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D012542:Scattering, Radiation; D013696:Temperature; D014867:Water / Q000737:chemistry
D011506:Proteins; D014867:Water; D008836:Micrococcal Nuclease