||Ligation-Dependent Picosecond Dynamics in Human Hemoglobin as Revealed by Quasielastic Neutron Scattering
Fujiwara, Satoru ,
Matsuo, Tatsuhito ,
Kono, Fumiaki ,
Journal of Physical Chemistry B
8077 , 2017-08 , ACS Publications
Hemoglobin (Hb) is a prototypical allosteric protein. We investigated the picosecond dynamics of the deoxy and CO forms of human hemoglobin using quasielastic neutron scattering to extract the dynamics changes upon ligation. From the analysis of the global motions, we found that, whereas the deoxy-form can be described by assuming translational and rotational diffusion of a rigid body, those of the CO form need to involve an additional contribution of internal large-scale motions. We also found that the local dynamics in the deoxy and CO forms are very similar in amplitude, but are slightly lower in frequency in the former than in the latter. Our results reveal the presence of rapid large-scale motions in hemoglobin, and further demonstrate that this internal mobility is governed allosterically by the ligation state of the heme group.