Conformational changes in melittin upon complexation with an anionic melittin analog.

Melittin and its Glu-(7,21,22,23,24) analog upon mixing in equimolar concentrations form a hybrid oligomer with significant helical structure, in conditions in which each peptide separately adopts a largely disordered structure. The hybrid exhibits both cold- and heat-induced denaturations similar to the phenomena exhibited by proteins. The hybrid also retains significant residual structure at higher temperature, similar to the 'molten globular state' that has been suggested for protein. Melittin, at concentrations in which it forms helical tetramers, also exhibits these phenomena and may be used as a model for protein-denaturation studies.