IDENTIFICATION OF A NEW VASCULAR SMOOTH-MUSCLE CONTRACTING POLYPEPTIDE IN PHONEUTRIA-NIGRIVENTER SPIDER VENOM

The fractionation of Phoneutria nigriventer spider venom by gel filtration (Sephadex G-10-120) followed by ion-exchange chromatography (microgranular CM-cellulose-52) resulted in sixteen fractions (C(I) to C(XVI)) from which C(VII+VIII), C(IX) and C(X+XI), caused dose-dependent and short-lived contractions of both arterial and venous rabbit vessels. Fraction Cx, x, was further purified by a reverse phase HPLC, and a contractile polypeptide (PNV2) was isolated. The amino terminal sequence of PNV2 (L A K RA D I C Q PG K T S Q R A C E T) indicated that it represents a pure polypeptide consisting of a single chain. Furthermore, the amino acid analysis of PNV2 revealed the presence of four disulfide bridges, a high content in Lys (14%), Glx (U%), and the absence of His. The global amino acid composition showed that this polypeptide is composed of 102 residues (Trp not included) with a calculated molecular weight of 12,114. Whether this peptide is responsible for the vascular alterations observed in Phoneutria envenomation, such as lung edema and priapism, remains to be further investigated.