Myosin was isolated from the hearts of 210-day-old genetically myopathic Syrian hamsters (Bio 53:58) and its properties compared to the myosin from random bred controls of the same age. The Ca2+ ATPase and the total-SH content did not differ significantly in the two groups. Myosin from myopathic animals showed a loss of LC2. Analyses of myofibrils and actomyosin revealed that the LC2 was present in these preparations from the myopathic animals and the loss of LC2 was taking place during the purification of myosin. Despite the presence of LC2 in the myofibrils and actomyosin, the corresponding ATPase activities were depressed in the myopathic hearts. The loss of LC2 in myopathic cardiac myosin was found to be due to high levels of neutral protease activity co-purifying with myosin. The protease fraction from myopathic hearts degraded the cardiac LC2 of control hamster and dog cardiac myosin, however, the Ca++ ATPase remained unchanged.
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine