Crude enzyme preparations
The upper and lower intestines,
pseudostomach and liver were homogenized (1:2
w/v) with 50 mM Tris – HCl buffer (pH 7.5) in an
ice water bath, using a tissue homogenizer. The
preparation was centrifuged at 10,000 × g for 15
min at 4°C. The floating lipid fraction was
removed and the aqueous supernatant was
recovered and kept at -20°C until used (Gimenez
et al., 1999).