Aspartic protease which cleaves several human serum proteins including hemoglobin, fibrinogen and albumin. Appears to cleave preferentially between P1 (Ala, Leu, Val, Phe and Gly) and P1' (Ala and Leu) residues. Inhibited by pepstatin A. Optimum pH is 5. Secreted into the gut lumen. Expressed in intestine, amphidal glands and excretory gland (at protein level). Expressed at the L4 larval stage and in adults. Not expressed at the L3 infective larval stage. Cleaved into a mature form. Belongs to the peptidase A1 family.