α-1:4-Glucosans. 10. Glycogen structure and rigor mortis in mammalian muscles

Abstract

The molecular structure of glycogen isolated by the Pfluger method from some mammalian muscles during the pre- and post-phases of rigor mortis has been examined by chemical and enzymic methods. Glycogen from pre- and post-rigor horse muscle tissues has an average chain length of approximately 17 glucose residues. This indicates a significantly lower degree of branching than is present in other samples of mammalian and invertebrate glycogen. The glycogen isolated from ox-sternocephalicus muscle after the onset of rigor mortis has significantly shorter exterior chains than that isolated from the pre-rigor muscle. This could indicate either partial inactivation of the enzyme system catalyzing the glycogenglucose 1-phosphate interconversion or a true heterogeneity of the glycogen in this muscle in vivo. The chemical and physiological significance of these observations is discussed. The possibility of the degradation of glycogen during alkaline extraction is considered.