Dermonecrotic toxins cleave the phosphodiester linkage between the phosphate and headgroup of certain phospholipids (sphingolipid and lysolipid substrates), forming an alcohol (often choline) and a cyclic phosphate (By similarity). This toxin acts on sphingomyelin (SM) (PubMed:15926888). It also acts on a broad range of lysophospholipids, like lysophosphatidylinositol (LPI), lysophosphatidylglycerol (LPG), lysophosphatidylethanolamine (LPE), lysobisphosphatidic acid (LBPA), lysophosphatidylserine (LPS) and lysophosphatidylcholines (LPC) of varying chain lengths (PubMed:15926888). The substrate preference is LPI > LPG > LPS > LPC >> LPE, LBPA (PubMed:15926888). Furthermore, the enzyme also act on cyclic phosphatidic acid and lyso-platelet activating factor (LPAF, an alkyl-LPC) (PubMed:15926888). The enzyme does not act on sphingosylphosphorylcholine (SPC, also known as lyso-sphingomyelin) and PAF (PubMed:15926888). The toxin may also act on ceramide phosphoethanolamine (CPE) (By similarity). It acts by transphosphatidylation, releasing exclusively cyclic phosphate products as second products (By similarity). It does not exhibit detectable PLA1/2 activity (PubMed:15926888). It induces dose-dependent hemolysis and dermonecrosis (PubMed:15926888). Also induces increased vascular permeability, edema, inflammatory response, and platelet aggregation (By similarity). an N-(acyl)-sphingosylphosphocholine = an N-(acyl)-sphingosyl-1,3-cyclic phosphate + choline an N-(acyl)-sphingosylphosphoethanolamine = an N-(acyl)-sphingosyl-1,3-cyclic phosphate + ethanolamine a 1-acyl-sn-glycero-3-phosphocholine = a 1-acyl-sn-glycero-2,3-cyclic phosphate + choline a 1-acyl-sn-glycero-3-phosphoethanolamine = a 1-acyl-sn-glycero-2,3-cyclic phosphate + ethanolamine Binds 1 Mg(2+) ion per subunit. Inhibited with low affinity by edelfosine. Expressed by the venom gland. Belongs to the arthropod phospholipase D family. Class II subfamily. Class IIa sub-subfamily. The most common activity assay for dermonecrotic toxins detects enzymatic activity by monitoring choline release from substrate. Liberation of choline from sphingomyelin (SM) or lysophosphatidylcholine (LPC) is commonly assumed to result from substrate hydrolysis, giving either ceramide-1-phosphate (C1P) or lysophosphatidic acid (LPA), respectively, as a second product. However, two studies from Lajoie and colleagues (2013 and 2015) report the observation of exclusive formation of cyclic phosphate products as second products, resulting from intramolecular transphosphatidylation. Cyclic phosphates have vastly different biological properties from their monoester counterparts, and they may be relevant to the pathology of brown spider envenomation.