PURIFICATION AND CHARACTERIZATION OF A SECRETED AMINOPEPTIDASE FROM ADULT ASCARIS-SUUM

A metalloaminopeptidase was identified in culture fluids collected dur ing in vitro cultivation of adult Ascaris suum. The enzyme was purifie d by anion-exchange and size-exclusion HPLC. The M-r of the enzyme was estimated at 293 kDa and consisted of subunits with M(r)s of 153 and 142 kDa. The isoelectric point of the aminopeptidase was 4.7. The amin opeptidase displayed a substrate preference for terminal arginyl resid ues. Aminopeptidase activity was also present in muscle, female reprod uctive tissue, pharynx, pseudocoelomic fluid and intestine. Among the various tissues, aminopeptidase activity was highest in the intestines ; the highest activity was found in culture fluids (three-fold higher than intestinal tissue). The aminopeptidase released by adult A. suum was enzymatically and biochemically identical to an aminopeptidase rel eased during in vitro development of A. suum third- to fourth-stage la rvae. Published by Elsevier Science Ltd on behalf of the Australian So ciety for Parasitology.