[Change of low-angle X-ray diffraction in the process of the transition of striated muscle into rigor]

A low-angle X-ray diffraction study of the frog striated muscle passing into rigor process was performed. It was established that at first in this process a Z-reflections intensity relative to those of the (10) and (11) reflections increases no less than ten times. Then Z and (11) reflections merge and a summary reflection (Z + 11) forms with a Z-reflection spacing. Before the merging of the Z and (11) reflections the (11) reflection intensity does not change relative to (10) reflection intensity. In rigor the (Z + 11) reflection is registered but not the (11) reflection. A conclusion is drawn that it is necessary to reconsider an interpretation of the change of intensity ratio of the main equatorial reflections when a muscle passes into rigor.