title: Lipid-induced changes in the secondary structure of snake venom cardiotoxins.
abstract: The secondary structures of three snake venom cardiotoxins (from Hemachatus hemachatus, Naja naja atra, and Naja naja naja), in aqueous solution and in a lipid-bound form, were investigated by Fourier-transform infrared spectroscopy. The conformation-sensitive protein infrared bands in the amide I region were analyzed using deconvolution and band-fitting procedures. The spectra of the three cardiotoxins in aqueous buffer are very similar; they indicate a high content of both antiparallel beta-sheet structure and unordered conformation. Moreover, component bands characteristic of turns can also be identified. The binding of cardiotoxins to bilayers of dimyristoylphosphatidyl-glycerol results in an increased content of a beta-structure at the expense of the nonordered conformation. It is suggested that lipid-induced conformational transitions to a beta-structure, similar to that observed with cardiotoxins, may be operative also in membrane interaction of other proteins and peptides, particularly with those which have a small tendency to form alpha-helices.
authors.affiliation: Division of Chemistry, National Research Council of Canada, Ottawa, Ontario.
authors.forename: W K
authors.initials: WK
authors.lastname: Surewicz
authors.forename: T M
authors.initials: TM
authors.lastname: Stepanik
authors.forename: A G
authors.initials: AG
authors.lastname: Szabo
authors.forename: H H
authors.initials: HH
authors.lastname: Mantsch
mesh_terms: D000818:Animals; D004546:Elapid Venoms / Q000032:analysis*; D005583:Fourier Analysis; D006321:Heart / Q000187:drug effects*; D008055:Lipids / Q000494:pharmacology*; D011487:Protein Conformation / Q000187:drug effects; D013055:Spectrophotometry, Infrared; D014118:Toxins, Biological / Q000032:analysis*
chemical_list: D004546:Elapid Venoms; D008055:Lipids; D014118:Toxins, Biological