Catalyzes the oxidation of glycerol 3-phosphate to dihydroxyacetone phosphate (DHAP), with a reduction of O2 to H2O2. The formation of hydrogen peroxide by this enzyme is crucial for cytotoxic effects on host cells. Does not show any dehydrogenase activity with NAD(+). O2 + sn-glycerol 3-phosphate = dihydroxyacetone phosphate + H2O2 Polyol metabolism; glycerol degradation via glycerol kinase pathway; glycerone phosphate from sn-glycerol 3-phosphate (aerobic route): step 1/1. Monomer.