Yh. Ji et al., Covalent structures of BmK AS and BmK AS-1, two novel bioactive polypeptides purified from Chinese scorpion Buthus martensi Karsch, TOXICON, 37(3), 1999, pp. 519-536
Complete amino acid sequences of two novel bioactive polypeptides, each con
taining 66 amino acid residues, BmK AS and BmK AS-1 purified from the venom
of Chinese scorpion Buthus martensi Karsch, have been determined by Edman
sequencing and mass spectrometry on native proteins, reduced and S-carboxym
ethylated proteins and their peptides obtained after cleavage with proteoly
tic enzymes. Sequence analysis showed 86.4% structural identity between BmK
AS and BmK AS-1 and also a high sequence similarity between BmK ASs and Aa
H IT4, a unique anti-insect toxin and a ligand of Na+ channels obtained fro
m Sahara scorpion A. australis Hector, but poor sequence homology between B
mK RSs and those of the known alpha-, beta-type and long-chain insect-selec
tive type scorpion neurotoxins. The positions of four disulfide bridges in
BmK AS-I were established as Cys-12 and Cys-62, Cys-16 and Cys-37, Cys-23 a
nd Cys-44, and Cys-27 and Cys-46, which are the same as those in alpha- and
beta-scorpion neurotoxins. These results suggest that BmK ASs and AaH IT4
may form a new group sharing similar structural and functional properties i
n the family of scorpion neurotoxic polypeptides. (C) 1999 Elsevier Science
Ltd. All rights reserved.