The ATP Assay Kit utilizes a couple of enzymes which catalyze the metabolism of glycerol to measure ATP levels in samples. First, glycerol kinase is used to convert glycerol to glycerol 3-phosphate. This step consumes ATP so the end product of this enzyme reaction can be used to quantify the amount of ATP present in the sample. In the next step, glycerol 3-phosphate oxidase reacts with glycerol 3-phosphate to produce hydrogen peroxide. The ATP level in the sample is determined by quantifying the hydrogen peroxide generated by the enzyme reaction with a fluorogenic probe that can be measured with a spectrophotometer.