| Popis: |
The present report indicates that a protein having saccharase activity can be purified from the contents of the silk glands (liquid silk) of the silkworm, Bombyx mori. The protein was purified by means of chromatography on Sephadex G-75, DEAE-cellulose and gel filtration on Sephadex G-200 column. The protein was shown to be homogenous by polyacrylamide disc electrophoresis. The enzymatic saccharase properties of this protein are the following: K m of 5.71 m m , an optimum pH of 6.5, a heat of activation at 30°C of 7.45 kcal mole−1 and a transition temperature of about 40°C. The activity of the saccharase is strongly inhibited with p- chloromercuribenzoate and activated by cysteine. The amino acid composition of the protein having saccharase activity is rich in glycine, asparatic acid, and glutamic acid. The molecular weight of the saccharase is estimated to be about 70,000. This purified protein contains about 2.4% carbohydrate. Sucrose is not detected in the liquid silk fraction. |
