L-Luciferin

L-Luciferin is the less active enantiomer (left-handed form) of the biologically active D-Luciferin, the most popular and versatile bioluminescent substrate. While, L-luciferin plays a biologically relevant role in the biosynthetic pathway of the firefly luciferin system, and can be enzymatically converted into the active D-luciferin, it acts as a weak alternative substrate. L-Luciferin can produce luminescence with firefly luciferase only under specific conditions, but the kinetics and efficiency differ greatly from D-luciferin. Due to that, L-Luciferin works as a competitive inhibitor.