The characterization of invertebrate troponin C

TNCs from lobster, mussel, and squid migrated with rabbit TNC at an apparent mol. wt of 18,000. Electrophoretic mobilities in the presence or absence of Ca2+ were compared: the electrophoretic mobility of rabbit TNC was greater in the presence of Ca2+ than it its absence, but all invertebrate TNCs tested migrated identically, whether Ca2+ was present or not. The Ca2+-binding capacity of invertebrate TNCs was only one Ca2+ ion per molecule. The alpha-helix contents in the presence or absence of Ca2+ were compared: rabbit TNC changed by a value of 16% and invertebrate TNCs by 4%. Antibodies to loligo TNC did not cross-react with rabbit TNC, but did interact with their molluscan TNCs.