Snake Venom Three
Finger Toxins (3FTx), An Overview
Snake
venom three finger toxins (3FTx), 51 to 83 amino acids in length, are
non-enzymatic members of the superfamily of three-finger protein domains1,2.
The group name for the superfamily derives from a common structural motif
resembling a hand with three fingers1,2. The three “fingers” are
β-strands connected to a central core. Typically the core contains four
conserved disulfide linkages. Snake venom three finger toxins may exist as
monomers and as covalently or non-covalently linked homodimers or heterodimers1,2.
Although 3TFx’s do not possess enzymatic activity, they do possess a wide range
of toxic and/or pharmacological properties. They include α-neurotoxins, β-cardiotoxins,
γ-neurotoxins, κ-neurotoxins, cytotoxins, fasiculins, mambalgins and
hannalgesin1,2.
κ-Bungarotoxin1-4
Illustrated
above is the ribbon structure of κ-Bungarotoxin, a 3TFx from the many banded
krait (Bungarus multicinctus). κ-Bungarotoxin is somewhat unique among
3FTx’s in that it possess 5 (instead of 4) disulfide linkages and exists as a
dimer1-3.
References
1)
Ferraz,
C. R., Arrahman, A., Xie, C., Casewell, N. R., Lewis, R. J., Kool, J., &
Cardoso, F. C., (2019). Multifunctional toxins in snake venoms and therapeutic
implications: from pain to hemorrhage and necrosis. Frontiers in Ecology and
Evolution, 7, 218.
3)
Dewan,
J. C., Grant, G. A., & Sacchettini, J. C. (1994). Crystal structure of.
kappa.-Bungarotoxin at 2.3-. ANG. resolution. Biochemistry, 33(44),
13147-13154.
