D-熒光素鉀鹽是熒光素酶的水溶性底物，存在于多種發(fā)光生物體中。在ATP和熒光素酶的催化作用下，D-熒光素鉀被氧化，產(chǎn)生藍綠色的光(560nm)，當(dāng)?shù)孜镞^量時，產(chǎn)生的光量子數(shù)與熒光素酶的濃度呈正相關(guān)。編碼熒光素酶的Luc基因是植物、哺乳動物細胞的常用報告基因。由于沒有背景干擾，因此可以很容易地檢測出低至0.02 pg 水平的熒光素酶。
D-熒光素鉀鹽是一類在生物體中發(fā)現(xiàn)的能引起生物發(fā)光的雜環(huán)化合物，如螢火蟲。在ATP存在下，螢光素酶將其氧化脫羧后會發(fā)光。化學(xué)研究中可用于熒光素酶的基板。
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.