title: High-resolution 1H-NMR studies of monomeric melittin in aqueous solution.
abstract: High resolution 1H-NMR at 360 MHz was used to characterize monomeric melittin in aqueous solution. The monomeric form of melittin was found to prevail at 3 mM concentration, pH 3.0, and temperatures between 30 and 90 degrees C, both in the absence of salt and with 6 M guanidium chloride. From comparison with model peptides and studies of the effects of 6 M guanidium chloride and variable temperature on the NMR parameters it was concluded that monomeric melittin is predominantly in an extended flexible form, with the fragments 5--9 and 14--20 more highly structured than the rest of the amino acid sequence. The appearance of a second, low abundant form of monomeric melittin, which is in slow exchange on the NMR time scale with both the more abundant monomeric conformation and aggregated melittin, was attributed to cis-trans isomerism of the peptide bond Leu-13--Pro-14.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001514:Bee Venoms; D001516:Bees; D019791:Guanidine; D006146:Guanidines; D009682:Magnetic Resonance Spectroscopy; D008555:Melitten; D008823:Micelles; D008968:Molecular Conformation; D012996:Solutions; D013237:Stereoisomerism; D013696:Temperature; D014867:Water
chemical_list: D001514:Bee Venoms; D006146:Guanidines; D008823:Micelles; D012996:Solutions; D014867:Water; D008555:Melitten; D019791:Guanidine