Required, with sphingomyelinase, to effect target cell lysis (hemolysis). a sphingomyelin + H2O = an N-acylsphing-4-enine + H(+) + phosphocholine Optimum pH is 6.0-7.5. Monomer. It has a high specificity for sphingomyelin, hydrolyzes lysophosphatidylcholine at a much lower rate, but has no activity towards phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. Belongs to the neutral sphingomyelinase family.