Oxalate decarboxylase (OxDC) is a Mn-dependent hexameric
enzyme that is highly important in management of
calcium oxalate mediated
nephrolithiasis. The present study reported the production and purification of OxDC from Pseudomonas sp. OXDC12 up to 45.3-fold with an overall yield of 7%. The purified OxDC displayed a single band of approximately 40 kDa on SDS-PAGE and 240 kDa on Native-PAGE suggesting it to be a hexameric
enzyme. The purified OxDC displayed an optimum activity at 26 °C and pH 4.5 in the presence of substrate
sodium oxalate (30 mg/mL) with a Km and Vmax value of 43.9 mM and 8.9 µmol/min, respectively and an activation energy of 52.49 kJ/mol. The
enzyme activity was significantly enhanced by adding
o-phenylenediamine to the reaction mixture. OxDC exhibited a very low 17 haemolytic activity which suggested a relatively safer therapeutic aspect of the tested OxDC. The structure prediction studies of the OxDC revealed a tertiary structure with α/β chains that formed the β barrel structure, typical of all cupin domains. The Ramachandran plot produced by PROCHECK shows that 90.5% of the residues are in the most favoured region and hence the OxDC model produced was a good one. Docking studies revealed the binding of the
metal ions and
ligands to cluster of three
histidine residues in the N terminal domain that formed the active site pocket of the
enzyme. It was suggested that the
histidine coordinated Mn2+ ion was critical for substrate recognition and binding and was also directly involved in OxDC catalyses.highlightsOxalate
decarboxylase (OxDC) was successfully purified from Pseudomonas sp. OXDC12 up-to 45.3-fold.The Km and Vmax values of the purified OxDC were calculated as 43.9 mM and 8.9 µmol/min, respectively.Genre analysis and structure prediction studies revealed the presence of β barrel structure typical of all cupin domains. The model exhibited a bi-cupin domain that forms the dimer of the homo-hexameric OxDC.Docking experiments revealed that the cluster of three HIS residues in the N terminal domain of the tested
enzyme formed the active site pocket for binding of Mn as well as the
ligands.Communicated by Ramaswamy H. Sarma.