title: The isolation and characterization of the tropomyosin binding component (TN-T) of bovine cardiac troponin.
abstract: The tropomyosin binding component (TN-T) of troponin was purified from bovine cardiac muscle using a combination of ion exchange chromatographies in the presence of urea. Sedimentation equilibrium experiments suggest a molecular weight for cardiac TN-T of 36 300 +/- 2 000, consistent with a value of 37 000 +/- 1 000 determining by polyacrylamide gel electrophoresis. Calculations based upon circular dichroism spectra indicate an apparent alpha-helical content of 43 +/- 3% for TN-T. Polyacrylamide gel electrophoresis and the effects of the calcium binding component (TN-C) upon the solubility of TN-T suggest that the two cardiac troponin components can interact with each other. Cosedimentation analysis of solutions containing cardiac tropomyosin and TN-T provide evidence for complex formation involving these two proteins. The data presented on the physical and chemical properties of TN-T, as well as the interaction studies indicate that the cardiac muscle regulatory system operates in a manner similar to that proposed for skeletal muscle.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002942:Circular Dichroism; D046911:Macromolecular Substances; D008970:Molecular Weight; D009124:Muscle Proteins / Q000302:isolation & purification; D009206:Myocardium / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D014335:Tropomyosin; D014336:Troponin / Q000302:isolation & purification
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin