BioThema is entirely focused on analytical applications of the firefly luciferase reaction whether it is detecting cells, measuring enzyme activity or something else. In this reaction luciferin is activated with ATP (adenosine triphosphate) and thereafter oxidized to oxyluciferin and CO2. The oxyluciferin is formed in an excited state and emits light when going to its ground state. The light is normally measured in what is called a luminometer.
In assays of ATP the light emission may be essentially constant or decay rapidly. Thus there are stable light and flash type ATP reagents based on the firefly luciferase reaction. At low levels of luciferase a negligible proportion of the ATP is consumed per minute and the light can then be almost constant but also low. At high levels of luciferase it is inevitable that ATP is consumed resulting in a rapidly decreasing light but initially the peak light is high. Actually the peak height and the decay rate are both proportional to the luciferase activity. BioThema has developed three types of ATP reagents66: