Heterodimer (A and B chains): phospholipase A2 that acts as a presynaptic neurotoxin and shows a PLA2 activity of 1377 umol/min/mg. In vivo, induces edema and produces neurotoxic symptoms in mice. Also exhibits indirect hemolysis, a strong myonecrotic activity and cytotoxicity. PLA2 catalyzes the calcium-dependent hydrolysis of the 2-acyl groups in 3-sn-phosphoglycerides. Monomer: Snake venom phospholipase A2 (PLA2) that shows a PLA2 activity of 578 umol/min/mg. a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycero-3-phosphocholine + a fatty acid + H(+) Binds 1 Ca(2+) ion. Heterodimer of A and B chain; non-covalently linked. The acidic protein (B chain) has phospholipase A2 activity and the A chain weakly inhibits the B chain enzymatic activity but potentiates its lethal potency. Expressed by the venom gland. in Dsm-a1. in Dsm-a1' which has only its protein sequence AA 17-27 sequenced. Monomer: DbTx-A alone is non-lethal, even at doses as high as 2 ug/g. Heterodimer (A and B chains): LD(50) is estimated to be about 0.1 ug/g by intraperitoneal injection into mice. Does not provoke hemorrhage. Belongs to the phospholipase A2 family. Group II subfamily. D49 sub-subfamily.