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Nakagawa, Hiroshi
no journal, ,
Protein dynamics is coupled with hydration water dynamics. Here, we examined the translational diffusion dynamics of protein hydration water by MD simulation and incoherent quasi-elastic neutron scattering at various hydration levels. The results of MD simulation show that the diffusion constants of hydration water are significantly suppressed below the hydration level at the percolation transition of hydration water. The diffusion constants are consistent with those estimated by neutron scattering experiments. The experimental data show that the hydration water dynamics can be described by a jump-diffusion model. The residence time in this model is correlated with the hydrogen bond kinetics between water molecules.
Kono, Hidetoshi; Yonetani, Yoshiteru; Ikebe, Kimiyoshi; Sakuraba, Shun; Ishida, Hisashi
no journal, ,
Metsugi, Shoichi*; Uenoyama, Atsuko*; Kubo, Jun*; Miyata, Makoto*; Kono, Hidetoshi; Yura, Kei*; Go, Nobuhiro*
no journal, ,
Ikebe, Kimiyoshi; Sakuraba, Shun; Kono, Hidetoshi
no journal, ,
Matsuo, Tatsuhito; Arata, Toshiaki*; Oda, Toshiro*; Fujiwara, Satoru
no journal, ,
The structural and dynamic properties of hydration water around F-actin and myosin S1 were investigated using small-angle neutron/X-ray scattering and quasi-elastic neutron scattering. S1 was shown to have typical hydration water, which has 10-15% higher average density with lower mobility than bulk water. On the other hand, F-actin was shown to have hydration water with unusual properties: the average density of the hydration water is at least 19% higher than that of bulk water and mobility is close to that of bulk water. These results indicate the diversity of hydration shell around proteins in terms of both structural and dynamic properties. The unusual hydration water around F-actin may be related to the suggested existence of "hyper-mobile water" around F-actin.
methodology for estimating localization of apurinic (AP) sites in DNA and its application to DNA exposed to ionizing radiationsAkamatsu, Ken; Shikazono, Naoya
no journal, ,
It is well-known that DNA lesions induced by ionizing radiation and chemicals can cause mutation and carcinogenesis. In particular, "clustered damage" site, that is a DNA region with multiple lesions within a few helical turns, is believed to hardly be repaired. However, chemical and spatial details of them are not known. We have developed a methodology for estimating localization of AP sites using fluorescence resonance energy transfer (FRET). We have recently found that experimentally-obtained FRET efficiencies for the heat-treated AP-DNA correspond to theoretical ones calculated on the basis of exponential distribution (a Poisson process). Now we are applying the FRET methodology to a plasmid irradiated with radiations such as 
Co 
-rays, 
He
, and 
C
ion beam. The results and the prospective will be discussed.
Ishida, Hisashi
no journal, ,
Murakami, Hiroshi
no journal, ,
no abstracts in English
Fujiwara, Satoru; Matsuo, Tatsuhito; Yamada, Takeshi*; Takahashi, Nobuaki*; Kamazawa, Kazuya*; Kawakita, Yukinobu; Shibata, Kaoru
no journal, ,