Circular dichroic spectra of elapid cardiotoxins.
Cardiotoxins isolated from elapid snake venoms constitute a chemically homogeneous family of molecules. Within this group several biologically different subclasses exist. We report a comparative analysis of the structure of 20 cardiotoxins using circular dichroism, immunological methods and secondary-structure prediction. It is shown that cardiotoxins fall within two structural subclasses. Toxins of group I are characterized by (a) CD spectra having an intense positive band close to 192.5 nm and a negative trough at 225 nm with no positive band around 230 nm, (b) strong cross-reactivity with a polyclonal antiserum specific for Naja nigricollis toxin gamma and (c) a high tendency to form a reverse turn in the region of position 11. Toxins of group II are characterized by (a) CD spectra displaying a much weaker positive band at 192.5 nm, a negative band around 210 nm and a positive band at 230 nm, (b) little cross-reactivity with the aforementioned antiserum and (c) a high reverse-turn potential at position 31. It is suggested that the observed differences result from differing curvatures in the antiparallel beta sheet which constitutes the main secondary structure of cardiotoxins.
Grognet
J M
JM
Service de Biochimie Commissariat à l'Energie Atomique Saclay, Gif-sur-Yvette, France.
Ménez
A
A
Drake
A
A
Hayashi
K
K
Morrison
I E
IE
Hider
R C
RC
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D007106:Immune Sera; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis; D011487:Protein Conformation
D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D007106:Immune Sera; D010455:Peptides