Question 19.3: Enzymatic Activity: Determining Optimum pH Enzymatic activit......
Enzymatic Activity: Determining Optimum pH
Enzymatic activity is shown for three different enzymes as a function of pH in the graph below. What is the optimum pH for pepsin (curve A), for urease (curve B), and for alanine dehydrogenase (curve C)?
ANALYSIS Recall that the optimum pH is the pH at which the enzyme shows the highest activity; therefore, the highest point on the curve, representing maximum activity, is the optimum pH for the enzyme.
Find the correct curve for each enzyme, then find the apex of the activity curve. Drop a vertical line to the pH axis and read the optimum pH directly from the axis scale. The optimum pH for pepsin is approximately 4.0, that for urease approximately 6.0, and that for alanine dehydrogenase approximately 9.5.