tDipeptidyl peptidases (DPPs) are widely distributed exopeptidases that hydrolyse the dipeptide moietiesfrom the N-termini of oligopeptide chains. In the present study, DPP-I was purified from germinatedmoong bean seeds via acid and ammonium sulphate precipitation followed by successive chromatogra-phies, that is, gel filtration (pH 7.4), cation exchange (pH 5.9) and anion exchange (pH 7.5). The purityof the enzyme was confirmed by native polyacrylamide gel electrophoresis (PAGE) and in situ gel assay.Purified plant DPP-I is a monomeric enzyme with a molecular weight of 38 kDa. It works optimally at pH7.0 and 40◦C, and it exhibits stability at pH ranging from acidic to slightly alkaline. Plant DPP-I preferen-tially hydrolyses glycine–arginine–4-methoxy--naphthylamide and various other synthetic dipeptidylsubstrates, but none of the studied endopeptidase and monopeptidase substrates. Inhibitory studiesrevealed the role of Cys and His amino acids in the catalytic mechanism. Functional studies of DPP-Irevealed the significant role of this glycoproteinous enzyme in protein mobilization during germination.