Myofibrillar proteins, enzyme activity and fibre types in human skeletal muscle.

The myofibrillar proteins and relative LC-3 content of myofibrils prepared from five different, left and right muscles of the human forearm were studied by electrophoresis in 10% SDS-polyacrylamide gels followed by densitometry. The specific K-activated ATPase activity of the myofibrillar myosin of the myofibrils was determined and the distribution of the fibre types was analyzed by histochemical methods. The qualitative pattern of the myofibrillar proteins was found to be identical in the different muscles; in the other parameters, however, a variation in a narrow range was observed. The relative LC-3 content, the ATPase activity and the type II fibre content of the right side muscles were always higher than those of the corresponding left side muscles.