Tregear R T, Terry C S, Sayers A J
J Muscle Res Cell Motil. 1984 Dec;5(6):687-96. doi: 10.1007/BF00713927.
Insect flight muscle fibres were relaxed by the combined action of MgAMPPNP and ethylene glycol, as measured by the stiffness of the fibres. Relaxation occurred over a small range of glycol concentration. Addition of Ca2+ raised the glycol required for relaxation. The speed at which the stiffness measurement was made did not influence the glycol concentration at which relaxation occurred. Glycol in excess of that needed to relax the muscle caused a slight rise in high-frequency stiffness. Removal of the glycol restored the rigor stiffness. Under glycol-relaxed conditions, much of the AMPPNP bound in muscle fibres was retained during cold-chase (elution of [3H] AMPPNP by nonradioactive AMPPNP); the intensity ratio of the inner equatorial X-ray diffraction peaks rose upon glycol relaxation to a value slightly below that characteristic of natural relaxation. The results are interpreted in terms of cooperative attachment of the crossbridges to actin.
通过测量纤维的刚度发现，MgAMPPNP和乙二醇的联合作用可使昆虫飞行肌纤维松弛。在较小的乙二醇浓度范围内会发生松弛。添加Ca2+会提高松弛所需的乙二醇浓度。进行刚度测量的速度并不影响发生松弛时的乙二醇浓度。超过使肌肉松弛所需量的乙二醇会导致高频刚度略有上升。去除乙二醇后，僵直刚度恢复。在乙二醇松弛条件下，冷追踪（用非放射性AMPPNP洗脱[3H]AMPPNP）过程中，肌肉纤维中结合的大部分AMPPNP会保留下来；乙二醇松弛时，赤道内X射线衍射峰的强度比会上升至略低于自然松弛特征值的值。这些结果是根据横桥与肌动蛋白的协同附着来解释的。
