2. An enzyme has a molecular weight of 47 kDa and a preparation that is 100% pure has a specific activity of 700 1.U./mg, at 25 C in a pH 7.5 phosphate buffer. The enzyme is known to be monomeric (one active site per enzyme molecule). (a) Calculate the mass of the pure enzyme preparation needed in 100mL of buffer (saturated with substrates) to produce a solution that will initially consume substrate at the rate of 5x107 M/min. (b) Calculate kcat for the enzyme. (c) A second preparation of this enzyme was tested for activity. In 100 mL of buffer, 1.6 mg of the solid enzyme was dissolved. This enzyme solution was mixed with a substrate solution in the ratio 500:1500 uL, and in the final solution, all substrates were present in great excess of their Km values. Absorbance spectroscopy showed that 0.32mM substrate was consumed per minute. Calculate the specific activity of the enzyme preparation