title: Cross-linking within the thick filaments of muscle and its effect on contractile force.
abstract: We have examined the effect of cross-linking on cross-bridge movement and isometric force in glycerinated psoas fibers. Two different methods, high-porosity gel electrophoresis and a fractionation technique, were used to follow the cross-linking of myosin heads (subfragment 1) and rod segments to the thick filament backbone. Contrary to earlier reports [Sutoh, K., & Harrington, W. F. (1977) Biochemistry 16, 2441-2449; Sutoh, K., Chiao, Y. C., & Harrington, W. F. (1978) Biochemistry 17, 1234-1239; Chiao, Y. C., & Harrington, W. F. (1979) Biochemistry 18, 959-963], we find that the heads of the myosin molecules are not cross-linked to the thick filament surface by dimethyl suberimidate. The time dependence of cross-linking rod segments within the core was monitored by a disulfide oxidation procedure to distinguish between intermolecular and intramolecular cross-linking. Comparison of the extent of the cross-linking reaction within myofibrils and the isometric force developed within fibers at various stages of cross-linking shows that isometric force is abolished in parallel with the formation of high molecular weight (cross-linked) rod species (greater than or equal to Mr 1000K). The myofibrillar ATPase remains virtually unaffected by the cross-linking reaction.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004120:Dimethyl Suberimidate / Q000494:pharmacology*; D007096:Imidoesters / Q000494:pharmacology*; D007537:Isometric Contraction; D007700:Kinetics; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D009210:Myofibrils / Q000187:drug effects / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D011817:Rabbits
chemical_list: D003432:Cross-Linking Reagents; D007096:Imidoesters; C024244:dithiobispropionimidate; D004120:Dimethyl Suberimidate; D000251:Adenosine Triphosphatases; D009218:Myosins