D-Luciferin potassium (D-Luciferin K Salt) is a popular bioluminescent substrate of luciferase in the presence of ATP.

METHODS: Preparation of D-Luciferin potassium for in vitro bioluminescence analysis:
1. Prepare 200× D-Luciferin reserve solution (30 mg/mL) with sterile water and mix gently until all dissolved. It can be used immediately after preparation or stored at -20℃.
2. Prepare 1× D-Luciferin (150 µg/mL) working solution in preheated tissue culture medium.
3. Aspirate the medium from the cultured cells.
4. Add 1× D-Luciferin solution to the cells before imaging. Incubate the cells at 37°C for a short period of time before imaging to increase signal.

METHODS: Preparation of D-Luciferin potassium for in vivo bioluminescence analysis:
1. Prepare a fresh 15 mg/mL D-Luciferin stock solution in DPBS. Sterilize by filtering with 0.20 um filter.
2. Inject 10 µL/g of mouse body weight. 150 mg D-Luciferin/kg body weight per mouse. For example, for a mouse weighing 10 g, inject 100 µL to provide 1.5 mg D-Luciferin.
3. inject D-Luciferin intraperitoneally 10-15 min prior to imaging. fluorescein kinetic studies should be performed for eah animal model to determine peak signal times.

Enolase activity assay is in the 2.0 mM MgSO4 and 400 mM KCl in the absence or presence of ENOblock or NaF, at 37°C by incubating pure enolase (3–9 U) in a buffer containing 50 mM imidazole-HCl (pH 6.8). The reaction is initiated by adding 1 μmol of 2-phospho-D-glycerate, and the OD is measured after 10 min of reaction time with a spectrophometer at 240 nm.