Five spots with similar molecular weights but distinct isoeleteric points were identified as a-enolase in the conditioned medium of HepG2 cells, indicating that at least five isoforms of this protein are secreted by these cells. The differences in these isoforms can be explained by the occurrence of post-translational modifications that alter the charge of side chains of the amino acid residues, such as the attachment of charged molecules to neutral residues or the addition of functional groups to charged residues. A pattern of aenolase isoforms very similar to that observed in our study was described in a proteomic analysis of pancreatic ductal cells. In that study, mass spectrometry analysis of the six spots identified as a-enolase showed several PTMs, namely the phosphorylation of one Ser residue, the acetylation of 26 Lys residues and the methylation of 21 Glu and 13 Asp residues. Furthermore, proteolysis of each of the spots resulted in both the posttranslationally modified peptides and their unmodified counterparts, suggesting that a myriad isoforms of a-enolase may arise from these combinations of PTMs. These observations suggest that a complex pattern of PTMs is also present in a-enolase secreted by hepatic cells. Additionally, the occurrence of other PTMs in enolase from HepG2 cells could not be ruled out since citrullination, Tyr and Thr phosphorylation, carbonylation, Tyr nitration, Cys glutathionylation and Lys malonylation have been also reported for a-enolase in different tissue specimens and experimental models. In this work, we showed for the first time that DENV AG-013736 infection not only increases the amount of a-enolase secreted by hepatic cells, but also shifts the distribution of isoforms towards the basic forms, indicating that infection modulates a-enolase PTMs. Modulation of a-enolase PTMs has been observed in other pathologies. In tumor cells, a-enolase shows more PTMs than those occurring in normal tissues, and some particular modifications, such as acetylation, methylation and phosphorylation in specific residues, appear to be associated with cancer development. In addition, increase in citrullinated forms of a-enolase has been reported in brain specimens of patients who died with Creutzfeldt-Jacob or Alzheimer’s diseases. Moreover, carbonylation, Tyr nitration and Cys glutathionylation were also aenolase PTMs observed in Alzheimer’s disease,. The role of the alteration in a-enolase isoform pattern during DENV infection and disease progression is a very interesting issue that requires further investigation. PTMs are known to modulate protein stability and activation, interfere with the catalytic activity of enzymes, determine cellular localization of proteins or address them for degradation, as well as regulate protein interactions with different types of ligands. Thus, PTMs determine the protein biological outcomes and orchestrate their role in different processes. However, in the case of a-enolase, very few studies assessed the effects of PTMs on its functions. Studies using rat cardiac muscles revealed that a-enolase enzymatic activity increases in alkaline phosphatase-treated samples, suggesting that phosphorylation has an inhibitory effect on its catalytic activity.