Dr. Murai Éva szerk.: Parasitologia Hungarica 12. (Budapest, 1979)

c) Haemoglobin splitting activity The proteolytic activity of liver fluke extracts was also examined on 2. 5% haemoglobin substrate, in different buffer systems generally employed for the assay of cathepsinlike and pepsin-like proteases, in acid medium, at pH optima characteristic oi certain cathepsines (MYCEK, 1970; RYLE, 1970). All measurements were additionaUy carried out in a cy stein-activated system. The results are shown in Table 4. Table 6 Effect of inhibitors on the BAEE-splitting activity of the liver fluke extracts (0.15M Tris-HCl buffer, containing 8. 3mM CaCl

2

; pH 7.8) Inhibitors BAEE-splitting activity U/g Inhibition % Inhibitors extract extract+inhibitor Inhibition % soybean trypsin inhibitor 0.001 % 0. 150 0.00 100 phenylmethylsulphonylfluoride 1 mM 0. 150 0. 062 58 tosyl- L-lysilchloromethane 1 mM 0. 150 0.00 100 Table 7 A comparison between the protease activities measured in media of flukes with open and closed oral suckers (Student's "t"-test) BAEE-splitting activity (U/ml) X S n P% oral sucker open 0. 278 * 0.258 7 < 5 oral sucker closed 0. 050 Í 0. 050 7 < 5 BTEE-splitting activity (U/ml) X S n P% oral sucker open 1. 071 t 0.396 7 < 5 oral sucker closed 0. 50 7 + 0.117 7 < 5 2 5