Determination of molecular mass and amino acid sequence The apparent molecular mass of the native purified protease (SU1) was measured using the calibration of Superdex 75 10/30 column as described by Zhang et al. (41). The apparent molecular mass of the denatured protease was determined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) as described by Laemmli and Favre (42) using a 5% (w/v) stacking gel and a 15% (w/v) separating gel. The molecular mass of cordysobin was estimated using a low molecular mass calibration kit as markers consisting of phosphatase b (94 kDa), bovine serum albumin (67 kDa), egg white ovalbumin (43 kDa), bovine carbonic anhydrase (30 kDa), soybean trypsin inhibitor (20 kDa), and bovine α-Lactalbumin (14.4 kDa).
Cordysobin was subjected to SDS-PAGE under reducing conditions and electrophoretically transferred to a polyvinylidene fluoride (PVDF) membrane (Millipore) by the method of Matsudaira (43). After the membrane was briefly stained by Coomassie Brilliant Blue R-250, the protein band was cut out and applied to an ABI Procise 492 protein sequencer (Applied Biosystems) (44).