AK Activity Assay kit can kinetically measure Adenylate Kinase activity by detecting adenosine triphosphate (ATP) generated from adenosine diphosphate (ADP) as a substrate. ATP is detected via a multi-step reaction, resulting in the generation of an intermediate that reacts with the Adenylate Kinase Probe forming an end product that can be measured colorimetrically (OD 570 nm) or fluorometrically (Ex/Em = 535/587 nm).