a phosphate monoester + H2O = an alcohol + phosphate Binds 1 Fe cation per subunit. Binds 1 Mn(2+) ion per subunit. Can also use Zn(2+), Cu(2+) and Mg(2+) ions. Optimum pH is 4.5. Homodimer; disulfide-linked. Belongs to the metallophosphoesterase superfamily. Purple acid phosphatase family.