Cross‐bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.
Cross‐bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.
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通过兔腰肌纤维中笼内 ATP 的光解研究 MgADP 存在下的跨桥动力学。
DOI：
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Y. Goldman
中科院分区：
文献类型：
--
作者：
J. Dantzig;M. Hibberd;D. Trentham;Y. Goldman
1. 在 MgADP 存在的情况下，在 MgADP 存在的情况下，使用激光脉冲光解笼中 ATP（P3-1（2-硝基苯基）乙基腺苷 5'-三磷酸），并在对僵直纤维施加小长度变化后，研究了 MgADP 与从兔腰肌中提取甘油的单纤维中的僵直桥之间的相互作用。 2. 在刚性纤维中添加 465 microM-MgADP 导致刚性张力降低 15.3 +/- 0.7%（S.E.M.，n = 13 种纤维的 24 次试验）。这种张力降低的半饱和值为 18 +/- 4 microM（n = 23，13 根纤维）。 3. 在不存在 Ca2+ 的情况下，通过在光解介质中加入 20 microM-2 mM-MgADP 来显着减缓笼中 ATP 的光解从严酷状态中的松弛。 4. MgADP 在介质中发生张力松弛的四个阶段：at，快速部分松弛（在预拉伸纤维中）；at，快速部分松弛（在预拉伸纤维中）； bt，放松减慢或紧张增加 50-100 毫秒； ct，突然加速松弛；和 dt，最终的、接近指数的松弛。 5. 不同 MgATP 和 MgADP 浓度下的实验表明，at 相是由于 MgATP 与无核苷酸跨桥结合所致。 6. bt 阶段通过在光解介质中包含 1-20 mM-正磷酸盐 (Pi) 或通过在光解前或 bt 阶段期间应用快速拉伸来缩写。这些结果表明，bt 和 ct 阶段是复杂的过程，涉及 ADP 解离、跨桥重新附着和涉及细丝滑动和 Ca(2+) 调节系统的协同脱离。 7. 将松弛的肌纤维拉伸至 3.2-3.4 微米的条纹间距，然后去除 ATP 并释放刚性纤维，直到张力降至松弛水平以下，从而可以研究负跨桥应变区域中松弛的应变依赖性。在 50 microM-2 mM-MgADP 和 10 mM-Pi 或 20 mM-2,3-丁二酮单肟存在的情况下，负应变跨桥的笼状 ATP 光解后的松弛速度比正应变跨桥快 6 至 8 倍。 A. F. Huxley (1957) 的模型预测了跨桥脱离的这种明显的应变依赖性。 8. 在存在 Ca2+ 的情况下，通过在培养基中添加 20-500 microM-MgADP，可以减缓笼中 ATP 光解后收缩的激活。在 MgADP 存在的情况下，与 MgATP 引起的跨桥脱离相关的初始张力下降被显着抑制。 9. 10 毫摩尔 Pi 在 MgADP 存在下部分抑制主动张力的产生。（摘要截断为 400 字）
1. The interaction between MgADP and rigor cross‐bridges in glycerol‐extracted single fibres from rabbit psoas muscle has been investigated using laser pulse photolysis of caged ATP (P3‐1(2‐nitrophenyl)ethyladenosine 5'‐triphosphate) in the presence of MgADP and following small length changes applied to the rigor fibre. 2. Addition of 465 microM‐MgADP to a rigor fibre caused rigor tension to decrease by 15.3 +/‐ 0.7% (S.E.M., n = 24 trials in thirteen fibres). The half‐saturation value for this tension reduction was 18 +/‐ 4 microM (n = 23, thirteen fibres). 3. Relaxation from rigor by photolysis of caged ATP in the absence of Ca2+ was markedly slowed by inclusion of 20 microM‐2 mM‐MgADP in the photolysis medium. 4. Four phases of tension relaxation occurred with MgADP in the medium: at, a quick partial relaxation (in pre‐stretch fibres); bt, a slowing of relaxation or a rise in tension for 50‐100 ms; ct, a sudden acceleration of relaxation; and dt, a final, nearly exponential relaxation. 5. Experiments at varied MgATP and MgADP concentrations suggested that phase at is due to MgATP binding to nucleotide‐free cross‐bridges. 6. Phase bt was abbreviated by including 1‐20 mM‐orthophosphate (Pi) in the photolysis medium, or by applying quick stretches before photolysis or during phase bt. These results suggest that phases bt and ct are complex processes involving ADP dissociation, cross‐bridge reattachment and co‐operative detachment involving filament sliding and the Ca(2+)‐regulatory system. 7. Stretching relaxed muscle fibres to 3.2‐3.4 microns striation spacing followed by ATP removal and release of the rigor fibre until tension fell below the relaxed level allowed investigation of the strain dependence of relaxation in the regions of negative cross‐bridge strain. In the presence of 50 microM‐2 mM‐MgADP and either 10 mM‐Pi or 20 mM‐2,3‐butanedione monoxime, relaxation following photolysis of caged ATP was 6‐ to 8‐fold faster for negatively strained cross‐bridges than for positively strained ones. This marked strain dependence of cross‐bridge detachment is predicted from the model of A. F. Huxley (1957). 8. In the presence of Ca2+, activation of contraction following photolysis of caged ATP was slowed by inclusion of 20‐500 microM‐MgADP in the medium. An initial decrease in tension related to cross‐bridge detachment by MgATP was markedly suppressed in the presence of MgADP. 9. Ten millimolar Pi partly suppressed active tension generation in the presence of MgADP.(ABSTRACT TRUNCATED AT 400 WORDS)
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DOI：
10.1073/pnas.82.3.658
发表时间：
1985-01-01
影响因子：
11.1
作者：
SIEMANKOWSKI, RF;WISEMAN, MO;WHITE, HD
通讯作者：
WHITE, HD
肌动球蛋白亚片段 1 ATP 酶的调节机制。
DOI：
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发表时间：
1987
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Rosenfeld,SS;Taylor,EW
通讯作者：
Taylor,EW
1-N6-乙烯腺苷二磷酸从受调节的肌动球蛋白亚片段 1 中解离。
DOI：
--
发表时间：
1987
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Rosenfeld,SS;Taylor,EW
通讯作者：
Taylor,EW
MgADP 与 acto-S1 结合和解离的速率。
DOI：
10.1016/0167-4838(85)90054-8
发表时间：
1985
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Borejdo,J;Ando,T;Burghardt,TP
通讯作者：
Burghardt,TP