title: The interaction of melittin with troponin C.
abstract: Melittin has been found to interact with troponin C with high affinity in the presence of Ca2+. The association constant approaches in magnitude that for melittin and calmodulin. The interaction results in a shift to lower wavelengths of the emission band of Trp-19 of melittin and in an increased shielding of Trp-19 from quenching. A major increase occurs in the alpha-helical content of combined melittin. Formation of the complex inhibits tryptic hydrolysis of the connecting strand. The properties of fluorescent labels attached to Met-25 and to AEDANS-98 are altered as a result of the interaction. It is concluded that the combined melittin makes extensive contact with the connecting strand and adjacent portions of the N- and C-terminal lobes.
mesh_terms: D000818:Animals; D001514:Bee Venoms / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002942:Circular Dichroism; D006868:Hydrolysis; D066298:In Vitro Techniques; D008555:Melitten / Q000378:metabolism*; D011487:Protein Conformation; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014336:Troponin / Q000378:metabolism*; D019209:Troponin C; D014364:Tryptophan
chemical_list: D001514:Bee Venoms; D002147:Calmodulin; D014336:Troponin; D019209:Troponin C; D008555:Melitten; D014364:Tryptophan; D002118:Calcium