title: Identification of the active site serine of the X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis.
abstract: The active site serine of the X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis (PepX) was identified. The enzyme was labeled by [3H]DFP, treated by CNBr and the resulting peptides were separated by reverse-phase-HPLC. The main radiolabeled peptide was sequenced. Ser-348, in the following sequence, Gly-Lys-Ser-Tyr-Leu-Gly, was identified as the active site serine. A sequence comparison between the active site of PepX and other serine proteases was made, showing only limited sequence homologies in this area. The consensus sequence surrounding the active site serine in the three known X-prolyl dipeptidyl aminopeptidases (mammalian DPPIV, yeast DPAB and PepX) is G-X-S-Y-X-G, where X is a non-conserved amino acid.
authors.affiliation: Unité Protéines, Station de Recherches Laitières, INRA 78352, Jouy-en Josas, France.
authors.forename: J F
authors.initials: JF
authors.lastname: Chich
authors.forename: M P
authors.initials: MP
authors.lastname: Chapot-Chartier
authors.forename: B
authors.initials: B
authors.lastname: Ribadeau-Dumas
authors.forename: J C
authors.initials: JC
authors.lastname: Gripon
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D001665:Binding Sites; D003488:Cyanogen Bromide / Q000494:pharmacology; D013294:Lactococcus lactis / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase; D012697:Serine Endopeptidases; D003488:Cyanogen Bromide