How does the luciferase enzyme speed up the chemical reaction?

The chemical reaction that results in bioluminescence requires two unique chemicals: luciferin and either luciferase or photoprotein. When luciferase binds to a chemical called luciferin. The interaction of the luciferase with oxidized (oxygen-added) luciferin creates a byproduct, called oxyluciferin. This reaction requires energy and releases light. The luciferase speeds up the reaction, which occurs in two steps: 

• The luciferin combines with adenosine triphosphate (ATP), found in all cells, to form luciferyl adenylate and pyrophosphate (PPi) on the surface of the luciferase enzyme.
• The luciferyl adenylate combines with oxygen to form oxyluciferin and adenosine monophosphate (AMP). Light is given off and the oxyluciferin and AMP are released.

The luciferin-luciferase chemical reaction has been used to measure the amount of ATP produced in cells.