ASSAY FOR IN-VIVO YEAST INVERTASE ACTIVITY USING NAF

The methods used for invertase activity determination are based on the measurement of glucose or reducing sugars produced by the enzymatic h ydrolysis of sucrose into glucose and fructose. When whole yeast cells are used in these assays, the monosaccharides formed by the action of the periplasmic enzyme can be taken up and metabolized, leading to er rors on the enzyme activity determination, This study reports a method for a more accurate invertase activity measurement by blacking the gl ycolytic pathway. In this method the cells were preincubated with 50 m M sodium fluoride, and inhibitor of enolase. This in vivo measurement of the enzyme activity, under initial rate conditions, was performed u sing cell concentrations up to 64 mg cell/ml. The results obtained sho wed that this method is particularly useful for cells with low inverta se activity. (C) 1996 Academic Press, Inc.