Isolation of f-actin filaments Comparison of f-actin filament preparations from normal and dystrophic mouse muscle

Abstract

To investigate the dystrophic influence on the characteristics of actin, a method for the isolation of F-actin filaments from the skeletal muscle of small sizes, i.e., <0.5 g, was devised. In this method, minced muscle was treated with collagenase and hyaluronidase, and the isolated filaments were washed with adenosine triphosphate (ATP). Upon examination in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the ATP-washed filaments showed a protein component identical in mobility to actin in untreated myofibrils or to that prepared by the conventional method. Electron microscopic appearances of the filaments were similar to those of F-actin filaments described in the literature. The dimensions of the filaments were 0.5–2.5 μm in length and 60–70 Å in diameter. The ability to activate the Mg-adenosine triphosphatase of myosin was found to be Ca 2+ independent. In all aspects of the above characteristics, the filaments from leg muscles of 129/Re dydy dystrophic mice and their litter mates were observed to be identical.