Purification Of Troponin Research Articles

Purification of troponin C isoforms from EDL and soleus muscles of the rat.

To date, there has been no report of rat TnC purification, despite the rat being an animal commonly used in physiological studies of mammalian muscle. In this study we isolated the fast and slow Troponin C isoforms from rat extensor digitorum longus (23 microg TnC/g wet weight) and soleus (17.6 microg TnC/g wet weight) muscles respectively. The rat Troponin C isoforms were shown to have identical electrophoretic properties to, and yield the same tryptic digestion products as commercial preparations of rabbit fast skeletal muscle and human cardiac muscle TnC isoforms.

A Study of Troponin, a Myofibrillar Protein from Rabbit Skeletal Muscle

Abstract Precipitation at pH 5.6 is found to improve the rabbit muscle troponin preparation. Further purification of troponin is achieved by treating troponin preparations with 0.1 m dithiothreitol, followed by the removal of contaminating tropomyosin by gel filtration. This is possible because through these purification procedures the molecular weight of tropomyosin as estimated by gel filtration remains fairly constant (approximately 130,000), while that of troponin preparations is gradually reduced from approximately 150,000 via 90,000 to 44,000. The sulfhydryl and tryptophan contents of troponin thus purified are 5.4 and 4.0 moles/105 g protein, respectively. Evidence is presented which indicates that tropomyosin and troponin form a complex which behaves exactly like the relaxing protein, and that the relaxing protein preparation is actually dissociated by 5 m urea into troponin and tropomyosin. The weight ratio of troponin to tropomyosin in the relaxing protein as estimated from the density of Amido black staining on gel electrophoresis is approximately 1:2.5. Precipitation of troponin by calcium and disaggregation of troponin by dithiothreitol support the view that, subsequent to calcium binding, troponin undergoes conformational change which is in turn transmitted through tropomyosin to the actin-myosin interaction.