Question

The cell-free extract prepared from e. Coli cells over-expressing enzyme -glucosidase showed the activity of 1.5 units per ml (protein concentration 2 mg per ml). The ni-nta purified preparation showed the activity of 75 units per ml (protein concentration 100 g per ml). Calculate the fold purification of the enzyme achieved?

Answer 1

When it comes to enzyme kinetics ie the rate of reaction of enzyme with surface, specific activity is defined as the amount of substrate enzyme converts per mg protein in enzyme preparation.   In this case we have to calculate Specific Activity. Specific activity : Divide total enzyme activity by total protein.  

Specific Activity :  75/2= 37.5

Fold Purification: Divide sp. act. by 8.2 (initial sp. act.).

37.5/8.2= 4.57