Catalyzes the hydrolysis of D-xylono-1,4-lactone-5-phosphate and L-arabino-1,4-lactone-5-phosphate. Also able to hydrolyze carboxy 1,4-lactones. a 1,4-lactone + H2O = a 4-hydroxyacid + H(+) D-xylono-1,4-lactone 5-phosphate + H2O = 5-phospho-D-xylonate + H(+) H2O + L-arabino-1,4-lactone 5-phosphate = 5-phospho-L-arabinonate + H(+) Binds 2 Zn(2+) ions per subunit. kcat is 23.4 sec(-1) with D-xylono-1,4-lactone-5-phosphate as substrate. kcat is 6.7 sec(-1) with L-arabino-1,4-lactone-5-phosphate as substrate. Belongs to the metallo-dependent hydrolases superfamily. Phosphotriesterase family.