Partial characterization of acidic proteinase in the midgut of parasarcophaga surcoufi larvae [Diptera: Sarcophagidae]

Activity of acidic proteinase in the midgut of larval Parasarcophaga surcoufi was investigated and partially characterized. Larval midgut extract showed a moderate acidic pH [pH 4] optimum for hydrolysis of hemoglobin. The proteolytic activity of the larval midgut was estimated by hydrolysis of hemoglobin and was found to be inhibited by pepstatin [aspartic proteinase inhibitor], dithiothreitol [DTT] and mercaptoethanol, while it was not inhibited by soybean trypsin inhibitor [STI] and EDTA. These characteristics may imply that cathepsin D-like proteinase is an effective acidic proteinase present in the Parasarcophaga surcoufi larval midgut