1998 Fiscal Year Final Research Report Summary
ANALYSIS OF SINGLE TURNOVERS IN THE CAGED-ATP EXPERIMENT ON SKINNED MUSCLE FIBERS
| Project/Area Number |
09670050
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | OITA MEDICAL UNIVERSITY |
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Principal Investigator |
HORIUTI Keisuke Oita Med.Univ., Associate Prof., 医学部, 助教授 (50183603)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEMORI Shigeru Jikei Univ.Sch.Med.Lecturer, 医学部, 講師 (20179675)
YAGI Naoto JASRI,SPring-8, Chief Scientist, 主席研究員 (80133940)
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| Project Period (FY) |
1997 – 1998
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| Keywords | skeletal muscle / contraction / skinned fiber / cross-bridge / caged ATP / photolysis / x-ray diffraction / synchrotron radiation |
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| Research Abstract |
A mechanical study on skinned rat muscle fibres was performed at <approximately equal> 16ﾟC involving x-ray diffraction and caged-ATP photolysis ; the amounts of photoreleased ATP were set lower than 0.2 mM.The main aim was to analyze the deactivation process in single turnovers of the cross-bridge ATPase. With regard to the phase of activation, the results under the single turnover condilions were generally consistent with our previous results obtained with larger amounts of photoreleased ATP.The mechanical activity of the muscle was monitored by the 90ﾟ-out-of-phase component of stiffness at 500 Hz. In the phase of deactivation, this stiffness decreased to zero with a t_<1/2> of 0.2-0.3 s. Judging from intensities of the x-ray reflections, a large number of cross-bridges turned into the strong binding structure with a t112 of 0.5-0.7 s. However, at this time, tension did not increase but was slowly decreasing with a t_<1/2> of <approximately equal>1.0 s. Our results indicate that many of the cross-bridges are not in the strong binding state during contraction, and that they produce little force even when they are deactivated and take the strong binding conformatio
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