【摘要】 肌原纤维是由粗丝和细丝重迭而成的Ａ带和只含细丝的Ｉ带组成，形成了天然光栅，因此可用光学方法探讨肌原纤维分子结构及其动力学问题。试验表明，单色光通过美洲蛙肌原纤维后，衍射光左右两端为非对称性，且左右条纹锋值间隔随肌原纤维节长度增大而减小。肌肉运动有张有弛，于是肌原纤维长度有变异，其变异与非对称有关。当肌原纤维长度增加时，左右两端强度差异变大，而相对应条纹的锋值间隔距离变小。这一现象与布拉格方程和折射定律所得结果一致。它表明了长度不同的肌原纤维具有不同的厚度和肌球蛋白和肌动蛋白密度，因而产生不同的折射率。更多还原

【Abstract】 Examined under the electron microscope,the myofibril was found to be made up of two kindsof smaller filaments, one about twice as thick as the other. The thicker filaments were shown toconsist mainly of protein myosin while the thinner filaments mainly of protein actin. Each filamentwas seen arrayed with another filament of the same kind and the two arrays of filaments overlappedfor part Of their length like a natural grating;It is apparently this overlap that gives rise to crossbands of the myofibril.The dense A-band consisted of the overlapping thick and thin filamentsand the light I-band consisted of thin filaments alone. In the present experiment,it was found that when a mono-chromatic light was used to passthrough the myofibrils of Rana pinpiens,the light diffraction intensity at both ends of the myofibrilappeared to be asymmetrical,the diffraction intensity became larger but the peak value distancebecame smaller.This phenomenon coincides with Bragg equation and the law of refraction. It wasindicated that there exists different thickness in the different length of the myofibrils and the myo-fibils may consist of different myosin and actin.更多还原