Protein degradation in human pure pancreatic juice analyzed by two-dimensional gel electrophoresis

Two-dimensional gel electrophoresis (2-DE) was used to study protein degradation in human pure pancreatic juice (PPJ) which was collected at 5 min intervals for 20 min by selective endoscopic cannulation of the main pancreatic duct. In PPJ collected from healthy subjects no significant degradation was observed by incubating PPJ at 37 degrees C up to 6 h. By further incubation for 24 h, glycoprotein-1, procarboxypeptidase A-1 and lipase were nearly completely degraded, while alpha-amylase and procarboxypeptidase B-1 were not degraded under these conditions; alpha-amylase became labile in the presence of 1 mM ethylene diaminetetraacetic acid (EDTA) or 10 mM phenyl methyl sulfonyl fluoride (PMSF). Protein degradation was observed by 2-DE of an initial fraction of PPJ collected from patients with chronic calcific pancreatitis (CCP). The 2-DE patterns of subsequent fractions resembled those of PPJ from healthy subjects. The mixture of the last fraction with the initial fraction showed significant protein degradation, inhibited by adding aprotinin. Furthermore, the extent of protein degradation correlated with the dilatation of the main pancreatic duct as a consequence of intraductal stagnation of pancreatic juice. These findings demonstrate that protein degradation in PPJ is accelerated by intraductal activation of serine proteases in the case of patients with CCP. 2-DE of PPJ from patients with CCP provides useful information for the evaluation of intraductal activation of zymogens and the progress of chronic pancreatitis.