Spectroscopic evidence of two melittin molecules bound to Ca2+-calmodulin.
According to Comte et al. (Comte, M., Maulet, Y. and Cox, J.A., (1983), Biochem.J., 209, 269-272), melittin (Mel) gives rise to a one:one complex. We evidence here, by fluorescence anisotropy and gel filtration binding assay (in the presence of 5 mM CaCl2 and 100 mM NaCl) the existence of two complexes: the well-known CaM.Ca4.Mel and a second CaM.Ca4.Mel2 which had not yet been reported. The affinity of Mel for the CaM.Ca4.Mel species is about three orders of magnitude lower than the affinity of Mel for the CaM-Ca4 species.
Laboratoire de Physique, U.A. 491 CNRS, Université Louis Pasteur, Faculte de Pharmacie, Strasbourg, France.
A
A
Follenius-Wund
Y
Y
Mely
D
D
Gerard
D000818:Animals; D001514:Bee Venoms / Q000032:analysis*; D002118:Calcium / Q000032:analysis*; D002147:Calmodulin / Q000032:analysis*; D002417:Cattle; D002850:Chromatography, Gel; D005454:Fluorescence Polarization; D008555:Melitten / Q000032:analysis*; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
D001514:Bee Venoms; D002147:Calmodulin; D008555:Melitten; D002118:Calcium