Dynamic behavior of oligomeric inorganic pyrophosphatase explored by quasielastic neutron scattering.
The purpose of this investigation is to determine whether a large oligomeric protein, inorganic pyrophosphatase (IPPase) from Thermococcus thioreducens with quaternary structural complexity, would have distinguishable dynamic characteristics compared to those of the small simple monomeric model protein, lysozyme. In this study, the β-relaxational dynamics of the two proteins, IPPase and lysozyme, are compared in the 10 ps to 0.5 ns time interval using quasi-elastic neutron scattering (QENS). Both of the protein dynamics show a characteristic logarithmic-like decay in the intermediate scattering function (ISF) of the hydrogen atoms. Distinguishable dynamical behavior found between two proteins reveals local flexibility and conformational substates unique to oligomeric structures. Moreover, the temperature dependence of the mean square displacement (MSD) of the hydrogen atoms in protein molecules, which is a traditional way to determine the "softness" of the protein molecule, is measured and shows no difference for the two proteins.
Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Xiang-qiang
XQ
Chu
Manavalan
M
Gajapathy
Kevin L
KL
Weiss
Eugene
E
Mamontov
Joseph D
JD
Ng
Leighton
L
Coates
D009113:Muramidase / Q000737:chemistry / Q000378:metabolism; D033363:Neutron Diffraction; D011755:Pyrophosphatases / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle; D019712:Thermococcus / Q000201:enzymology; D013816:Thermodynamics
D009113:Muramidase; D011755:Pyrophosphatases