title: On the intensity reversal of the "tropomyosin reflexions" in X-ray diffraction patterns from crab striated muscle.
abstract: X-ray diffraction patterns have been recorded from skinned single fibres obtained from crab leg muscle, and the outer parts of layer-lines indexed as orders of 38.5 nm, which have been assigned to tropomyosin and actin, were examined. Fibres at normal length in the presence of ATP (gamma-S), and over-stretched fibres in rigor solutions, show no intensity reversal of the 2nd and the 3rd layer-lines when the Ca2+ concentration is raised. The results are discussed with reference to the mechanism of Ca2+ regulation. Fibres in the presence of Mg-ADP and vanadate ion (Vi) and fibres pretreated at low pH, though generating no substantial tension at high Ca2+ concentration, give rise to rigor-like patterns which are dependent on Ca2+ concentration.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D003386:Brachyura; D002118:Calcium / Q000378:metabolism; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D013873:Thionucleotides / Q000494:pharmacology; D014335:Tropomyosin / Q000502:physiology*; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D013873:Thionucleotides; D014335:Tropomyosin; D014639:Vanadium; C022571:adenosine 5'-O-(3-thiotriphosphate); D014638:Vanadates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium