Dynamical behavior of proteins observed by neutron scattering; Quasielastic neutron scattering study of muscle thin filaments

Fujiwara, Satoru; Matsuo, Tatsuhito; Yamada, Takeshi*; Shibata, Kaoru  

Protein dynamics is indispensable for functions of proteins. Elucidation of the functions of the proteins thus requires elucidation of the protein dynamics. Neutron scattering provides a tool to measure directly the protein dynamics. Here we investigated the dynamics of muscle thin filaments using quasielastic neutron scattering to investigate the role of the dynamics in the regulatory mechanism of muscle contraction. We carried out neutron scattering experiments on the native thin filaments (NTF) in the presence and absence of Ca and F-actin using the dynamics analysis spectrometer at J-PARC. It was shown that NTF in the -Ca state is more flexible than in the +Ca state, and that this difference arises from the different distributions of the local atomic motions. Comparison with F-actin suggests that the differences arise from the regulatory proteins. These results imply that regulation of the protein dynamics plays an important role in the regulatory mechanism of muscle contraction.