Dr. Kassai Tibor - Dr. Murai Éva szerk.: Parasitologia Hungarica 10. (Budapest, 1977)

Fig. 3 Effect of incubation time on the mammalian chymotrypsin inactivation by the worm extracts o/o 100 •a c 10 15 30 45 minutes The residual activity of added chymotrypsin was determined after 15-minute incubation with the test material, because the interaction of chymotrypsin with its specific inhibitor is timedependent (Fig. 3). Incubation was not necessary with added trypsin, because the trypsin-inhibitor is acting immediately.Both trypsin and chymotrypsin became inactivated on incubation with intact larvae in nutrient medium, or on addition to enzyme-free incubation medium from which the larvae had been removed. In those experiments in which enzyme was added to KRT, TS or TC 135 media containing parasites, the mean activity decrease was 8. 3 and 6.7 units with chymotrypsin and trypsin, respectively, over 24 hours. The amount of inhibitor released by the parasites was found to depend on the composition of the medium (Tables 3 and 4), but was unrelated to its pH. While the pH of the media having a good buffer capacity fell only by 0. 2-0. 4 grade steps from 0 to 24 hours, it decreased by as much as 1. 5-2. 4 grades in the Tyrode solution without any notable change in inhibitor activity. Neither the trypsin-inhibitor, nor the chymotrypsin-inhibitor became inactivated on 30-minute heat treatment at 56°C (Figs 1 and 2), and 5%TCA failed to decrease inhibitor activity in either nutrient media or extracts. On saturation with ammonium sulphate, the inhibitor activity was separated in the filtrate at 0. 6 degree of saturation.