Purification of S. levis major whole midgut proteinase
TenS. levis larvaeweremaintainedat4 8Cfor5 min, dissectedand
the whole midgut were homogenized in buffer containing Tris–HCl
10mM,NaCl150 mMand2%TritonX-100,pH7.4(2 ml).Themixture
was centrifuged at 6000 g for 30 min. The soluble fraction was
applied to a DEAE-Sephadex column (25 cm 1 cm) equilibrated
with0.1MTris–HCl,pH8.0.Theproteinswereelutedwith1.0 MNaCl
in the same buffer. The protein elution profile was followed by UV
absorbance(280 nm).Afterproteinelution,dialysiswasperformedin
a buffer containing 10mMTris–HCl and 50mMNaCl, pH 8.0.