Content and synthesis of several abundant glycolytic enzymes in skeletal muscles of normal and dystrophic mice.

In both 2- and 3-month-old 129 ReJ mice, the catalytic activity levels of three enzymes involved in glycogen breakdown (phosphorylase, enolase, and aldolase) were found to be 35-50% lower in hind limb muscles of dystrophic mice as compared with normal mice. The reduced activities of these enzymes in the diseased tissue was directly due to corresponding reductions in the number of enzyme molecules rather than being due to inactivation of the enzymes in the dystrophic muscle. Results of short term double isotope incorporation experiments conducted with muscle explants in vitro suggested that the rates of synthesis of these enzymes, and of most other abundant cytosolic proteins, relative to each other, were similar in hind limb muscles of normal and dystrophic mice. The present work on murine muscular dystrophy is discussed in terms of our previous studies into the influence of avian muscular dystrophy on the content and synthesis of abundant glycolytic enzymes in chicken skeletal muscles.