The 19 kDa protein (KAZ) of Oplophorus luciferase is a catalytic component.
The crystal structure of a mutant KAZ (nanoKAZ) was determined.
The structure consists of 11 β-strands and 4 α-helices, forming a β-barrel.
The structure of nanoKAZ is similar to those of fatty acid-binding proteins.
The coelenterazine-binding site might be in a central cavity of the protein.