This is an alternative activity of the firefly luciferase (EC 1.13.12.7), which the enzyme exhibits under normal conditions only when acting on the L-enantiomer of its substrate. The D-isomer can act as a substrate for the CoA---ligase activity in vitro only under low oxygen conditions that are not found in vivo. The activation of L-firefly luciferin to a CoA ester is a step in a recycling pathway that results in its epimerization to the D enantiomer, which is the only substrate whose oxygenation results in light emission.
Viviani VR, Scorsato V, Prado RA, Pereira JG, Niwa K, Ohmiya Y, Barbosa JA
Title
The origin of luciferase activity in Zophobas mealworm AMP/CoA-ligase (protoluciferase): luciferin stereoselectivity as a switch for the oxygenase activity.