Amino‐Acid Sequence of the α‐Subunit of Taipoxin, an Extremely Potent Presynaptic Neurotoxin from the Australian Snake Taipan (Oxyurunus s. scutellatus)

Abstract

The amino acid sequence of the .alpha.-subunit of taipoxin, an extremely potent presynaptic neurotoxin from the Australian snake taipan, was determined. The basic protein, by itself a moderately neurotoxic phospholipase, consisted of a single polypeptide chain of 119 amino acids. The main fragmentation of the reduced and S-carboxymethylated derivative was accomplished by cleavage with Staphylococcus aureus V8 protease and trypsin. Chymotryptic peptides and cyanogen bromide fragments were used to align and complete the sequence, which was determined by automated Edman degradation. The taipoxin .alpha.-subunit was closely homologous to the other taipoxin subunits and to other elapid snake venom phospholipases A2.