Yoel Romero looks like he is next for Michael Bisping, while Luke Rockhold and Ronaldo Souza are still waiting in the wings; the Ultimate Fighting Championship does not need another 185-pound power player right now....
In biology, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of residues that form temporary bonds with the substrate (binding site) and residues that catalyse a reaction of that substrate (catalytic site).
Each enzyme will only speed up one reaction as the shape of the enzyme molecule needs to match the shape of the molecule it reacts with (the substrate molecule). The part of the enzyme molecule that matches the substrate is called the active site.