Arma. Meki et al., A BRADYKININ-POTENTIATING PEPTIDE (PEPTIDE K(12)) ISOLATED FROM THE VENOM OF EGYPTIAN SCORPION BUTHUS-OCCITANUS, Peptides, 16(8), 1995, pp. 1359-1365
A nontoxic peptide with bradykinin-potentiating activity was isolated
from the dialyzed venom of the scorpion Buthus occitanus by reverse-ph
ase high performance liquid chromatography (RP-HPLC). The pharmacologi
cal activity of the peptide was bioassayed by its ability to potentiat
e added bradykinin (BK) on the isolated guinea pig ileum as well as th
e isolated rat uterus for contraction. Moreover, the peptide potentiat
es in vivo the depressor effect of BK on arterial blood pressure in th
e normotensive anesthetized rat. Chemical characterization of the pept
ide was also performed. The amino acid composition of the peptide show
ed 21 amino acid residues per molecule including three proline residue
s. The amino acid sequence of the purified peptide was confirmed by ma
ss spectrometry. Either N- or C-terminal ends were free. The sequence
does not show a homology with bradykinin-potentiating peptides isolate
d from either scorpion or snake venoms. Furthermore, we did not find a
significant sequence homology between the sequence of the isolated pe
ptide and any of proteins or peptides in GenPro or NEW data banks. The
peptide also inhibited angiotensin-converting enzyme (ACE), and could
not serve as substrate for the enzyme. It could be concluded that the
mechanism of bradykinin-potentiating peptide (BPP) activity may be du
e to ACE inhibition.