Conformational stability of a snake cardiotoxin.
A snake cardiotoxin from the venom of the Formosan cobra, Naja naja atra, is a basic polypeptide. The protein can be denatured in 6.0 M guanidine hydrochloride or at elevated temperatures. Its conformation remains virtually the same in solvents of lower polarity than water such as 1, 2-ethanediol or 1-propanol and 1, 2-ethanediol (1:1 v/v). The circular dichroism spectrum is atypical in water in that the peptide chromophores show a small negative CD band at 214 nm and a large positive one at 195 nm. To some extent the CD pattern resembles that of the beta-form but differs in specific positions and magnitudes. Considering that the theoretical CD of the reverse beta-bend and the characteristics of model polypeptides in beta-form manifest a similar pattern, we suggest that cobra cardiotoxin is rich in beta structure including beta pleated-sheets and beta reverse-turns.
D000818:Animals; D002942:Circular Dichroism; D004546:Elapid Venoms / Q000032:analysis*; D006321:Heart / Q000187:drug effects*; D010455:Peptides / Q000032:analysis; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014118:Toxins, Biological / Q000032:analysis*
D004546:Elapid Venoms; D010455:Peptides; D014118:Toxins, Biological