In driving forward biosynthetic reactions the hydrolysis of pyrophosphate to orthophosphate is import such as the synthesis of DNA. For this enzyme, a unit of activity is defined as the amount of enzyme that hydrolyzed 10 μ mol of pyrophosphate in 15 mins at 37 degrees C under standard assay conditions. This hydrolytic reaction is catalyzed in E. coli by apyrophosphatase that has a mass of 120 kd and consists of six identical subunits. The purified enzyme has a Vmax of 2800units per milligram of enzyme.
1. Determine the numbers of moles of substrate are hydrolyzed per second per milligram of enzyme when the substrate concentration is much greater than KM?
2. Determine the numbers of moles of active sites are there in 1 mg of enzyme? Suppose that each subunit has one active site.
3. Calculate the turnover number of the enzyme?