STRUCTURAL STUDIES OF MUSCLE TRANSIENTS

肌肉收缩的核心奥秘在于， mysoin头（横桥）将储存的能量转化为机械能量， 工作 X射线衍射是为数不多的生物物理技术之一 其允许收集关于 生理相关的MS时间尺度和这些类型的实验 实际上是同步辐射最早的应用之一。 之一 这些实验的目的是检测结构变化 由于快速同步的肌肉交叉桥的作用， 机械瞬变 到目前为止，这些实验仅限于 非常强的反射，例如基于肌球蛋白的14.3 nm反射 赤道。 我们最近获得了2 ms时间分辨数据， 第一次显示， 反射（主要在5、9和5.1nm层线上）， 肌肉交叉桥的同步动作。 通过测量 2.72 nm的抛物面反射的位置作为 在给定的快速释放后，我们还能够 测量肌丝的瞬时弹性、数量 这是希望模拟肌肉的肌肉生理学家的强烈兴趣。 我们能够在BioCAT光束线上获得优质数据 并且正在尝试使用 肌动蛋白、肌球蛋白和原肌球蛋白的已知晶体结构。

The central mystery of muscle contraction is how the enzymatic mysoin heads (crossbridges) convert the energy stored into mechanical work. X-ray diffraction is one of the few biophysical techniques which allows collection of structural information on the physiologically relevant ms time scale and these kinds of experiments were in fact one of the first uses of synchrotron radiation. One of the goals of these experiments has been to detect structural changes due to the action of muscle crossbridges synchronized by rapid mechanical transients. Such experiments so far have been limited to very strong reflections such as the myosin-based 14.3 nm reflection and the equator. We recently obtained 2 ms time resolved data that showed, for the first time, intensity changes in actin -based reflections (mainly on the 5,9 and 5.1 nm layer lines) due to synchronized action of muscle crossbridges.. By measuring changes in the position of the 2.72 nm meridional reflection as a function of the residual force after a given quick release, we were also able to measure the instantaneous elasticity of muscle filaments, quantities of intense interest to muscle physiologists who wish to model muscle. We were able to obtain excellent quality data on the BioCAT beamline and are in the process of attempting to model this data using the known crystal structures of actin, myosin and tropomysosin.