D-luciferin is the natural substrate of the enzyme luciferase (Luc), that catalyzes the production of the typical yellowgreen light of fireflies.The present review covers the synthesis of D-luciferin and derivatives or analogues that are substrates or inhibitors of the luciferase from the American firefly Photinus pyralis , the enzyme more frequently used in techniques of in vitro and optical imaging.
D-Luciferin exhibits a decrease in the measured K _m in PC3M-Luc cell lysates with a K _m of 34 μM.

Bioluminescence imaging (BLI) using the firefly luciferase (Fluc) as a reporter gene and D-luciferin as a substrate is currently the most widely employed technique. The total signal intensity is plotted against the time after D-luciferin injection to generate a time-intensity curve. In addition to the peak signal, the signals at fixed time points (5, 10, 15, and 20 min) after D-luciferin injection are determined as alternatives to the peak signal. The signal in a given time-intensity curve is normalized for the peak signal in the curve to represent the pattern of temporal changes after D-luciferin injection.
Inject with 10 μL of D-luciferin (intraperitoneally or intravenously) stock solution per gram of body weight: normally ~200 μL for a 20 g mouse for a standard 150 mg/kg injection.
Thaw D-Luciferin (either Potassium or Sodium Salt) at room temperature and dissolve in dPBS (no calcium or magnesium) to a final concentration of 15 mg/mL. Pre-wet a 0.22 μm filter by drawing through 5-10 mL of sterile H ₂ O and discard water. Sterilize the D-Luciferin solution through the prepared 0.22 μm syringe filter.