Conformational changes in troponin induced by Ca ++

Abstract

Troponin undergoes reversible changes in fluorescense emission intensity and emission maximum when Ca ++ concentration is varied between 10 −5 and 10 −4M at pH 7.5 and 25°. These changes suggest infolding of tryptophan fluorophores of the protein into hydrophobic regions as Ca ++ concentration is increased. A Ca ++-induced change in light scattering also occurs, indicating an aggregation of the protein, but the dependency on Ca ++ concentration and the kinetics of the aggregation process suggest that it follows in time the Ca ++-induced conformational changes in troponin.