Snake venom metalloproteinase that inhibits the classical complement pathway dose-dependently. It acts by binding to carbohydrates of IgG within the antibody-sensitized sheep erythrocytes (EA) complex, and thus prevents interaction of component C2 with immobilized C4b. Also induces cation-independent hemagglutination that can be prevented by D-galactose pretreatment. Binds 1 zinc ion per subunit. Heterotrimer; disulfide-linked. The heterotrimer consists of 1 metalloproteinase chain and 2 lectin chains (Probable). Expressed by the venom gland. N-glycosylated. Does not show proteolytic activity on rabbit IgG, human C3 and C4 complement components, fibrinogen, beta-casein, hemoglobin, ferritin, myoglobin, chymotrypsinogen, and melittin. Belongs to the venom metalloproteinase (M12B) family. P-III subfamily. P-IIId sub-subfamily.