Amino-terminal truncation of procalcitonin, a marker for systemic bacterial infections, by dipeptidyl peptidase IV (DP IV)

Increased concentrations of procalcitonin (PCT) are found in the plasma of patients with thermal injury and in patients with sepsis and severe infecti on, making this molecule important as a diagnostic and prognostic marker in these diseases. Interestingly, only the truncated form of PCT, PCT(3-116), is present in the plasma of these patients. The enzyme responsible for thi s truncation is unknown as yet. Here, using capillary zone electrophoresis, mass spectrometry and Edman sequence analysis, we demonstrate that dipepti dyl peptidase IV (DP IV, EC 3.4.14.5) is capable of catalyzing the hydrolys is of PCT(1-116), releasing the N-terminal dipeptide Ale-Pro. We hypothesiz e that PCT(3-116) is the result of the hydrolysis of PCT(1-116) by soluble DP IV of the blood plasma or by DP IV expressed on the surface of cells. (C ) 2000 Federation of European Biochemical Societies.