A Highly Active
Anticomplement Factor from the Venom of Naja kaouthia
SUN Qian-Yun, LU Qiu-Min, WANG Wan-Yu, XIONG Yu-Liang*
( Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223,China
)
Abstract A highly
active anticomplement factor (cobra venom factor) from the venom of Naja
kaouthia in South Yunnan, China was isolated by sequential column chromatography
(SP-Sephadex-C-25, Q Sepharose HP and Sephadex G-150). It displays strong
anticomplement activities in vitro and in vivo, and has
anticomplement activity of 1 515 u per mg. The purified anticomplement factor
was homogeneous on SDS-PAGE with a molecular weight of 149 kD.It is composed of
three polypeptide chains which are connected by disulfide bonds. The molecular
weights of the three chains were determined to be 65.4 kD (α-chain), 52.1 kD
(β-chain), and 35.5 kD (γ-chain). The γ-chain displayed size heterogeneity, and
two bands could be clearly detected in gels. All polypeptide chains were
stained with periodate Schiff reagent, suggesting the presence of carbohydrate.
Neutral sugar and sialicacid were determined to be 1.78% and 0.38%, respectively.
The isoelectric point of this anticomplement factor was 6.2. Its amino acid
composition was analyzed and N-terminal amino acid sequence of each polypeptide
chain was determined.
Key words anticomplement factor； complement； venom
*Corresponding author： Tel, 86-871-5192476； Fax, 86-871-5191823； e-mail, [email protected]