Flexible Regions in Myosin Head and the Energy Transduction in Muscle Contraction

荧光标记试剂4-氟-7-氨磺酰基苯并呋咱（ABDF）特异性标记肌球蛋白亚片段-1（S-1）的Cys-707（SH 1）。疏水性荧光染料3- [4-（3-苯基-2-吡唑啉-1-基）苯-1-磺酰氨基]苯基硼酸（PPBA）与S-1的ATP结合口袋以几何构型结合。这两种荧光团可用作检测S-1柔性区域的灵敏探针。这些数据表明，运动的SH 1与ATP水解。此外，PPBA的实验清楚地表明，S-1的ATP结合口袋在ATP水解过程中呈现收紧的构象状态。因此，这两个柔性区域负责肌肉收缩中的能量转换系统。

The fluorescent labeling reagent 4-fluoro-7-sulfamoylbenzofurazan (ABDF) specifically labeled Cys-707 (SH1) of myosin subfragment-1 (S-1) . The hydrophobic fluorescent dye 3- [4- (3-phenyl-2-pyrazolin-1-y1) benzene-1-sulfonylamido] phenylboronic acid (PPBA) atoichiometrically bound to the ATP-binding pocket of S-1. These two fluorophores were useful as sensitive probes to examine the flexible regions of S-1. The data suggested a movement of SH1 associated with ATP hydrolysis. Furthermore, the experiments with PPBA clearly demonstrated that the ATP-binding pocket of S-1 assumes a tightened conformational state during ATP hydrolysis. Thus these two flexible regions are responsible for the energy transduction system in muscle contraction.