Enolase is a key glycolytic enzyme that catalyzes the dehydration of 2-phosphoglycerate to phosphoenolpyruvate. Recently, enolase was revealed as an important protein in pathophysiological processes since it was found on the surface of hematopoietic cells and overexpressed in several tumor cells. Our previous studies demonstrated that alpha-enolase is up-regulated in pancreatic ductal adenocarcinoma (PDAC). In this present work, we further characterized the alpha-enolase from PDAC and normal pancreatic duct cells by mass spectrometry using LTQ-Orbitrap and identified multiple post-translational modifications of alpha-enolase, such as phosphorylation, acetylation, and methylation. The result showed that more acetylated lysines, methylated aspartic acids, and glutamic acids were found in PDAC cells than that of normal pancreatic duct cells.