title: Biochemical properties and expression profile of human prolyl dipeptidase DPP9.
abstract: Dipetidyl peptidase 9 (DPP9) is a prolyl dipeptidase preferentially cleaving the peptide bond after the penultimate proline residue. The biological function of DPP9 is unknown. In this study, we have significantly improved the yield using Strep.Tactin purification system and characterized the biochemical property of DPP9. Moreover, the dimer interaction mode was investigated by introducing a mutation (F842A) at the dimer interface, which abolished the enzymatic activity without disrupting its quaternary structure. Furthermore, DPP9 was found ubiquitously expressed in fibroblasts, epithelial, and blood cells. Surprisingly, contrary to previous report, we found that the expression levels of DPP8 and DPP9 did not change upon the activation of the PBMC or Jurkat cells. These results indicate that the biochemical property of DPP9 is very similar to that of DPP8, its homologous protease. DPP9 and DPP8 are likely redundant proteins carrying out overlapping functions in vivo.
authors.affiliation: Division of Biotechnology and Pharmaceutical Research, National Health Research Institutes, No. 35, Keyan Rd., Zhunan Town, Miaoli County, Taiwan.
authors.forename: Hung-Kuan
authors.initials: HK
authors.lastname: Tang
authors.forename: Hsiang-Yun
authors.initials: HY
authors.lastname: Tang
authors.forename: Shu-Ching
authors.initials: SC
authors.lastname: Hsu
authors.forename: Yue-Ru
authors.initials: YR
authors.lastname: Chu
authors.forename: Chia-Hui
authors.initials: CH
authors.lastname: Chien
authors.forename: Chin-Hang
authors.initials: CH
authors.lastname: Shu
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D017931:DNA Primers; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D013379:Substrate Specificity
chemical_list: D017931:DNA Primers; C471241:DPP9 protein, human; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases