Question

Aspartase enzyme is used industrially for the manufacture of aspartic acid, a component of low-calorie sweeter. Ammonium fumarate are converted to aspartic acid. The conversion can be described using Michaelis-Menten kinetics with Km=4.0 g/L. The substrate solution contains 150 g/L ammonium fumarate. Enzyme is added into the solution, and the reaction is stopped when 85% of the substrate is converted. At 32°C, vmax,0 for the enzyme is 5.9 g/L/h and its half-life is 10.5 days. At 37C, vmax,0 increases to 8.5 g/L/h but the half-life is reduced to 2.3 days. Which operating temperature would you recommend?

Answer 1

The initital concentration of substrate s₀ =150 g l^-1

The final substrate concentration s_f = 0.15 s₀

= = 22.5 g l^-1

Calculating the deactivating rate constant at 32^oC using equation,

For enzyme subject to deactivation, the batch reaction time is evaluated using equation,

At 37^oC, the deactivation rate constant is:

The batch reaction time is:

=As the batch reaction time is lower at 37^oC, 37^oC is the recommended operating temperature.