Dipeptidyl peptidase IV (DPPIV/DPP4), is also known as CD26 (cluster of differentiation 26 or T-cell activation antigen CD26), or adenosine deaminase complexing protein 2. It is a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. DPP4 plays a key role in glucose metabolism, immune regulation, signal transduction and apoptosis. It is responsible for the degradation of incretins such as GLP-1 and hence its inhibition by drugs such as Sitagliptin have been used for treatment of diabetes mellitus type 2. DPP4 also appears to work as a suppressor in the development of cancer and tumors.

Dipeptidyl Peptidase IV Activity Assay Kit provides a simple, reproducible, and sensitive tool of measuring the activity of Dipeptidyl Peptidase IV in cell lysates, plasma, serum, urine, saliva and other biological liquid samples. In this assay, Dipeptidyl Peptidase IV cleaves a synthetic specific substrate releasing a fluorophore. The fluorescence signal is measured at Ex/Em = 360/460 nm. The increase in fluorescence intensity is directly proportional to Dipeptidyl Peptidase IV activity in the sample.

• Microplate reader capable of measuring fluorescence intensity at Ex/Em = 360/460 nm
• Precision pipettes to deliver 2 µL to 1 mL volumes
• Incubator at 37°C
• Tubes to prepare sample dilutions
• 15 mL and 50 mL conical tubes
• MilliQ water or another type of double distilled water (ddH₂O)

1. Add 20 µL of samples, positive control, substrate background to the 96-well microtiter plate.
2. Add 30 µL assay buffer to each well.
3. Add 100 µL of standard to the 96-well microtiter plate.
4. Initiate the reaction by adding 50 µL diluted DPPIV substrate solution to each well. Do NOT add to standard wells. Carefully shake the plate for a few seconds to mix well.
5. Measure fluorescence signal. For kinetic reading: Immediately start measuring fluorescence intensity at Ex/Em=360/460 nm continuously at 37°C and record data every 5 min for 30 min.