Periplasmic form of dipeptidyl aminopeptidase IV fromPseudoxanthomonas mexicanaWO24: purification, kinetic characterization, crystallization and X-ray crystallographic analysis

Abstract

Dipeptidyl aminopeptidase IV (DAP IV or DPP IV) fromPseudoxanthomonas mexicanaWO24 (PmDAP IV) preferentially cleaves substrate peptides with Pro or Ala at the P1 position [NH2-P2-P1(Pro/Ala)-P1′-P2′…]. For crystallographic studies, the periplasmic form of PmDAP IV was overproduced inEscherichia coli, purified and crystallized in complex with the tripeptide Lys-Pro-Tyr using the hanging-drop vapour-diffusion method. Kinetic parameters of the purified enzyme against a synthetic substrate were also determined. X-ray diffraction data to 1.90 Å resolution were collected from a triclinic crystal form belonging to space groupP1, with unit-cell parametersa= 88.66,b= 104.49,c = 112.84 Å, α = 67.42, β = 68.83, γ = 65.46°. Initial phases were determined by the molecular-replacement method usingStenotrophomonas maltophiliaDPP IV (PDB entry 2ecf) as a template and refinement of the structure is in progress.