Purification and biochemical characterization of a novel secretory dipeptidyl peptidase IV from porcine serum.

Abstract

Purification of DPP-IV enzyme from porcine serum, is presented in this study for the first time. The high molecular weight DPP-IV from porcine serum was fractioned using Sephadex G-75 gel filtrationfollowed by DEAE Sephadex anion exchange and Sephadex G-100 gel filtration chromatography columns with a final yield of 11.25%. The SDS-PAGE of the purified sample showed a single band of molecular mass nearing 160kDa. Distinct single band was observedafter PAS staining confirmed it to be a glycoprotein. The purified enzyme showed an optimum pH and temperature of 8 and 37°C, respectively. The enzyme effectively cleaved fluorogenic substrate Gly-Pro-AMC with Km and Vmax of 4.578µM and 90.84 nmoles/min, respectively. Purified DPP-IV activity was inhibited by Diprotin A with an IC50 value of 8.473µM. Among the three plant extracts used to study DPP-IV inhibition, the aqueous hot extract of Terminalia chebula showed the highest inhibition of 87.19%, followed by the aqueous cold extract of Momordica carantia, ( 31.6%) and Azadirachta indica (34.16%) at the concentration of 25µg.