Purification and properties of protease inhibitors from developing embryos of Hemileuca oliviae (Ckl)

A perchloric acid extract of eggs of Hemileuca oliviae inhibits bovine trypsin, kallikrein and papain, as well as the native proteolytic activity (pH 7.0) of the developing embryo. Specificity is indicated by the lack of inhibition of other proteases. The amount of inhibitory activity changes during embryological development, reaching a maximum around 23 days, when the larva is fully developed. The inhibitory activity was lost by dialysis and was destroyed by ashing (450°C, 18 h) but was unaffected by exposure to 97°C for 3 min. The presence of two protease inhibitors was detected in the perchloric acid extract. The principal component has a molecular weight of approx. 9000 and its heat sensitivity is affected by pH. At the present time the role of these inhibitors in the developing embryo is unknown. Some trypsin-like native protease activity occurs in the egg during embryogenesis and may thus be the target enzyme in vivo.