Formation of an enzyme-substrate complex increases the rate of reaction.

Explain how.

A scientist measured the rate of removal of amino acids from a polypeptide with and without an enzyme present. With the enzyme present, 578 amino acids were released per second. Without the enzyme, 3.0 × 10−9 amino acids were released per second.

Calculate by how many times the rate of reaction is greater with the enzyme present. Give your answer in standard form.

Answer = ______________ times faster

Another scientist investigated an enzyme that catalyses the following reaction.

ATP → ADP + Pi

The scientists set up two experiments, C and L.

Experiment C used • the enzyme • different concentrations of ATP.

Experiment L used • the enzyme • different concentrations of ATP • a sugar called lyxose.

The scientists measured the rate of reaction in each experiment. Their results are shown in Figure 5.

Calculate the rate of reaction of the enzyme activity with no lyxose at 2.5 mmol dm−3 of ATP as a percentage of the maximum rate shown with lyxose.

Answer = ______________ %

Lyxose binds to the enzyme.

Suggest a reason for the difference in the results shown in Figure 5 with and without lyxose.