Dendrotoxins and BPTI-like Proteins

Abstract

The dendrotoxins are a family of homologous proteins that are isolated from mamba snake venoms: namely, α-dendrotoxin (α-Dtx, β2-Dtx, γ-Dtx, and δ-Dtx from the venom of the Eastern green mamba (Dendroaspis angusticeps), two closely related peptides, toxin I and toxin K, from the venom of the black mamba (Dendroaspis polylepis plylepis), and Dv14 from the Western green mamba venom (Dendroaspis viridis) (Harvey and Karlson, 1980; 1982; Joubert and Taljaard, 1980: Strydom, 1973: Benishin et al., 1988; Harvey and Anderson, 1991) . They consist of 57–60 amino acids residue in single polypeptide chains, containing three intramolecular disulfide bonds. The crystal structure of α-dendrotoxin has been solved (Skarzynski, 1992). Dendrotoxins are highly homologous to Kunitz-type serine proteinase inhibitors, such as bovine pancreatic trypsin inhibitor (BPTI or aprotinin) (see Fig. 1). However, BPTI does not have K+ channel-blocking properties (Marshall and Harvey, 1992), and although dendrotoxins inhibit some proteinase (Marshall and Harvey, 1990), this amy be unrelated to their ability to block K+ channels. More recently, three dendrotoxins homologues, the kalicludines, were isolated from the sea anemone: Anemonia sulcata (Schweitz et al., 1995). They are several orders of magnitude less active than toxin I, and they may be more closely related to proteinase inhibitors.KeywordsNegative DeflectionMotor Nerve TerminalRepetitive FiringTissue BathSnake Venom ToxinThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.