1991 Fiscal Year Final Research Report Summary
A Rapid-freeze Electron Microscopy in Biological Materials
| Project/Area Number |
01480541
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
分子遺伝学・分子生理学
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| Research Institution | Okazaki National Research Institutes (1990)
Tokyo Metropolitan Organization for Medical Research (1989) |
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Principal Investigator |
TSUKITA Shoichiro Okasaki National Research Institutes, Prof., 生理学研究所, 教授 (50155347)
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| Co-Investigator(Kenkyū-buntansha) |
TSUKITA Sachiko Okazaki National Research Institute, assistant Prof., 生理学研究所, 助手 (00188517)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Caged compounds / Electron Microscope / Myosin / Rapid freezing / Liquid helium / ATP |
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| Research Abstract |
The interaction between myosin subfragment 1(Sl)and actin filaments after the photolysis of P^3-1-(2-nitrophenyl)ethyl ester of ATP(caged ATP)was analyzed using a newly-developed freezing system with liquid helium. Actin and Sl(100g mu each)formed a rope-like double helix characteristic of rigor in the presence of 5 mM caged ATP at room temperature. A UV flash with a half duration time of 0.3 ms photoreleased -0.8 mM of ATP. At 15 ms after photolysis, the rope-like double helix was partially disintegrated. S1 on actin filaments gradually decreased in number up to 35 ms after photolysis and their association was in a somewhat cooperative manner. No more changes of Sl attached on actin filaments were detected from 35 to 200 ms. At 1 min after photolysis, ATP was consumed and the rope-like double helix was reformed. Taking recent analyses of actomyosin kinetics into consideration, we concluded that most Sl observed on actinfilaments at 15-200 ms are so called "weakly-bound Sl"(SL. ATP or Sl. ADP. Pi)and that the gradual decrease of the weakly-bound Sl during 15-35 ms is due to the transition from the rapid equilibrium of actin. Sl. ATP/SI. ATP to that of actin. Sl. ADP. Pi/Sl. ADP. Pi.
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[Publications] Higuchi, M., Mitsuno, T., Sugimoto, M., Okamaoto, A., Hirose, S., Tsukuta, Sh. and Osawa, T.: "Tumoricidal activitiy of lymphotoxin (tumor necrosis factor) in vivo : Its effects on macrophages." J. Biological Response Modifiers. 7. 619-630 (1989)
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