Chapter 52 - Snake Venom Peptides

Abstract

This chapter focuses on nonenzymatically active peptides and toxins derived from the venom of snakes. Snake venoms are complex mixtures of small molecules, peptides, and proteins. The peptides belong to several structural classes, and they have many different biological actions. Most of the biologically active toxins are peptides or enzymes. The three-finger toxins were isolated from venoms of cobras and sea snakes because of their potent muscle paralyzing activity. They have 60–74 amino acid residues in a single chain cross-linked by four or five disulfide bonds. The α-neurotoxins are found in venoms of snakes of the Elapidae (cobras, kraits, mambas, etc.) and Hydrophidae (sea snakes) families, although similar molecules occur in venoms of some Colubridae. The a-neurotoxins bind to nicotinic acetylcholine receptors. The short and long α-neurotoxins paralyze skeletal muscle by blocking the ability of the neurotransmitter acetylcholine to bind to and activate the nicotinic receptors at the neuromuscular junction. These α-neurotoxins are among the most potent of venom constituents and presumably evolved to help elapid and hydrophid snakes catch their prey.