Mangrove catsnake

Denmotoxin is a snake venom protein produced by Boiga dendrophila (mangrove catsnake) that belongs to a family of well studied three-fingered neurotoxins.

Introduction

B. Dendrophila monomeric toxin (Denmotoxin) is the primary protein of snake venom used by Boiga dendrophila. This colubrid snake lives in Southest Asian lowland rainforest and mangrove swamps using birds as its primary prey.

One of the most well characterized snake venom protein families is the Three-finger-toxins (3FTX). These proteins have three β-stranded finger-like loops, stabilized by four disulphide bridges on the surface of a globular core. In non-convential 3TFXs a fifth disulphide bridge can be present as is the case in Denmotoxin. Denmotoxin is a non-covalent monomer.

How the overall structure looks like? Subunits orientation, chains: the number and relative positions, etc.

Denmotoxin belongs to a family of curaremimetic neurotoxins

Structure

Denmotoxin is a monomeric protein possessing 77 amino acid residues including 10 cysteines. Multiple sequence alignment of denmotoxin reveals that the venom belongs to the family of non-conventional 3FTXs. Compared to conventional 3FTxs denmotoxins has 7 additional amino acids. The calculated mass of the protein is 8507.8 Da. Has . Belongs to a family of non-conventional 3FTXs (3 finger toxins). Denmotoxin has 7 additional amino acid residues in its N-terminal when compared to other elapid 3FTXs; the N-terminus is also blocked by a pyroglutamic acid residue. There are two highly flexible regions on the protein: one at the tip of the central loop and one at the 3 first residues of the N-terminus.

Denmotoxin interacts with acetylcholine-receptors

Biochemistry of denmotoxin is unique for its specifity to bird nicotinic acetyl choline receptors. Binding of denmotoxin to chick muscle AcHR (α1βγδ) is a highly irreversible where as interaction with identical subunit assembly in mouse AcHR was reversible. Here a picture of the complex where the toxin is bound to the AChR. The active sites which interact with the receptor.

Active site organisation

Conclusions

Snake venom can kill!