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Correlations between the mechanical and biochemical processes of muscle contraction by photogeneration of ATP.

ATP 光生成引起的肌肉收缩的机械和生化过程之间的相关性。

基本信息

批准号：
62480108
负责人：
YAMADA Kazuhiro
金额：
$ 4.22万
依托单位：
大分医科大学
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62480108/
关键词：
skinned muscle fiber Ruby laser caged ATP ATP muscle stiffness cross-bridge ethylene glycol active tension of muscle Caged ATP 収縮の動力学エチレングリコールルビーレーザグリセリン処理筋アクトミオシンリン核磁気共鳴法

项目摘要

Correlations between the mechanical and biochemical processes of muscle contraction, and the effect of the solvent on them, have been studied.Skinned muscle fibers in the rigor state were incubated in a solution containing P^3-1(2-nitro)pherlethyl-ATP, 'caged ATP' an inert photolabile precursor of ATP, and free Ca^<2+> concentration of either <lO^<-8>M of -30 uM. The mechanical response of the fibers was recorded during relaxation, as well as during the active contraction, initiated by liberating ATP with a pulse of 347 nm light from a frequency-doubled ruby laser. When ethylene glycol was included in the solution to 10%, the transient rise of tension during relaxation reported by Goldman, Hiberd & Trentham (1984) was markedly suppressed. Stretching fibers before photolysis changed the time course of the early parts of the tension transients but with relatively less effect on the later phases or on stiffness.The tension records from stretch and isometric trials converged to a final common time course of relaxation. Analysis of the convergence of tension records provided a means for measuring the cross-bridge detachment rate from the thin filament as a function of ATP concentration. The apparent second-order rate constant for detachment was at least 5xlO^5 M^<-1> s^<-1> at 20ﾟC, and this rate was the same in ethylene glycol. When Ca^<2+> was included the medium, active tension was produced. Analysis of the tension records in terms of sequential detachment and reattachment reactions, provided a measure of cross-bridge reattachment rate and an alternate measure of the detachment rate. The rate of cross-bridge reattachment leading to force production, as well as the steady active tension, was reduced to 70% in ethylene glycol. These results indicated that a solvent-protein interaction is involved in the cross-bridge reattachment and force generation.

研究了肌肉收缩的力学和生化过程之间的关系以及溶剂对这些过程的影响。在僵直状态下，去皮的肌肉纤维在含有P^3-1(2-硝基)苯乙基-三磷酸腺苷的溶液中孵育，笼式三磷酸腺苷是三磷酸腺苷的惰性不耐光前体，游离钙离子浓度为-30微米。记录了纤维在松弛和主动收缩过程中的机械响应，这是由倍频红宝石激光以347 nm的脉冲光释放三磷酸腺苷所引发的。当溶液中乙二醇量为10%时，Goldman，Hiberd&Trentham(1984)所报道的松弛过程中的瞬时张力升高被显著抑制。在光解前拉伸纤维改变了张力瞬变早期的时间进程，但对后期或硬度的影响相对较小。拉伸和等长实验的张力记录会聚为最终的共同松弛时间进程。张力记录的收敛分析提供了一种测量作为ATP浓度函数的跨桥从细丝上剥离的速率的方法。在20ﾟC时，脱附的表观二级速率常数至少为5×10~(-5)M^~(-1)；S~(-1)~(-1)，在乙二醇中也是如此。当含有Ca~(2+)时，产生主动张力。根据连续的脱离和再附着反应对张力记录进行分析，提供了一种跨桥再附着率的测量方法，并提供了一种脱落率的替代测量方法。在乙二醇中，跨桥再附着率降低到70%，从而产生作用力和稳定的主动张力。这些结果表明，溶剂-蛋白质相互作用参与了跨桥重附着和力的产生。