Mamba toxins

This chapter describes biological and pharmacological properties of all pep tides from mamba venoms, and relates them to their amino acid sequences cla ssified in two main structural groups. In the first group, which is constit uted by peptides homologous to the basic pancreatic trypsin inhibitor (BPTI ), there are dendrotoxins, powerful blockers of Kv1 channels with a strong central neurotoxicity; protease inhibitors with weaker activity on K+ chann els and calcicludines which are blockers of HVA Ca2+ channels with a potent selective effect on a L-type Ca2+ channel in cerebellar granule neurons. T he second group contains all peptides which are structurally homologous to curaremimetic alpha-neurotoxins: short and long alpha-neurotoxins; muscarin ic toxins which are the unique peptides known to act selectively as agonist s or antagonists on one or several of the five muscarinic receptors known; anticholinesterases; `angusticeps-type' peptides with low toxicity and unkn own properties; and calciseptines which are specific blockers of L-type Ca2 + channels mainly in the cardiovascular system. In a third group are classi fied peptides of miscellaneous sizes and structures. The function of most o f them has not yet been elucidated. The peculiar interest of the relations between spatial structure and function is illustrated with four peptides fr om mambas. A method for the purification of all peptides from mamba species is described.