Firefly Luciferase is one of several fluorescent proteins. Other common ones are Green Fluorescent Protein, Renilla Luciferase, and Bacterial Luciferase.
Firefly luciferase catalyzes the oxidation of luciferin, the substrate in fireflies that makes them light up. The oxidation of luciferin, which is when oxygen is fused with the luciferin, happens in two steps. First the luciferin bonds with Mg2and ATP to create luciferyl adenylate and PPi (Pyrophosphate). Then the luciferyl adenylate reacts with diatomic oxygen to create oxyluciferin, AMP, and light.
Luciferase is interesting because of its compact two-part domain structure. The active site of luciferase is thought to be located in the cleft between the C and N-terminuses (Fig. 5). The C-terminus is the smaller part of luciferase, and it has the free carboxyl group. The larger N-terminus has the free amine group. During the reaction, luciferase undergoes a reversible conformational change, where the cleft between the C and N-terminus close up. This prevents water from entering the reaction and hydrolyzing one of the reactants.
In the theorized interaction that I modeled, the two very separate domains of luciferase are very important to the interaction. Because they split easily into the two separate terminuses, it allows my idea for a split catalyst genetic-specific biocatalyst. The recombination of the two domains is central to the idea and dependent on the two very separate domains.
 Conti, Elena, Peter Brick, and Nick P Franks. “Crystal structure of firefly luciferase throws light on a superfamily of adenylate-forming enzymes.” Structure 4.3 (1996): 287-298. Print.