Identification of the active site serine of the X‐prolyl dipeptidyl aminopeptidase from Lactococcus lactis

[摘要]

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.

[学科分类] 生物化学/生物物理

[关键词] X-prolyl dipeptidyl aminopeptidase;Serine protease;Active site;Diisopropylfluorophosphate;Lactococcus lactis.;TFA;trifluoroacetic acid;DFP;diisopropylfluorophosphate;DPAB;yeast dipeptidyl aminopeptidase B;DPPIV;dipeptidyl peptidase IV;PepX;X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis;PVDF;polyvinylidene difluoride;PTH;phenylthiohydantoin