Question

Figure 8: ONP Formation v. Enzyme Conc. Enzyme Abs @ concentration 420 nm (units/ml) 0.2 0.372 0.4 0.648 0.6 0.923 0.8 0.004 1.0 1.572 Examine Figure 8. In this experiment, all five samples were supposed to be subjected to identical conditions (substrate concentration, temperature, reaction time) except for the enzyme concentration, which is indicated in the table. Which of the following procedural errors could account for the unexpected result for the 0.8 units/ml enzyme concentration? This tube was left in the 37° water bath for 20 minutes instead of 10. The tube received three times as much substrate, which caused saturation. The enzyme inhibitor (Na2CO3) was added before the incubation period rather than after. O All of these are possible errors.

Answer 1

The correct answer is inhibitor was added before the incubation period rather than after. In this case, an inhibitor is the most logical explanation since adding a lot of substrate wont avoid the formation of ONP. Of course, after saturation the enzyme wont catalyze the reaction but we should already find any signal of the ONP.