Structural difference between group I and group II cobra cardiotoxins: X-ray, NMR, and CD analysis of the effect of cis-Proline conformation on three-fingered toxins

Natural homologues of cobra cardiotoxins (CTXs) are classified into two structural subclasses of group I and II based on the amino acid sequence and circular dichroism analysis. However, the exact differences in their three-dimensional structures and biological significance remain elusive.