Isolation,purification and biochemical characterization of dipeptidyl peptidase-III from germinated Vigna radiata seeds

Genome analysis of plants indicated majority of putative protease genes that need characterization at enzymatic and molecular level. Proteases execute important role in seed development but knowledge of dipeptidylpeptidases in seeds is limited. A dipeptidylpeptidase-III that cleaves Arg-Arg from Arg-Arg-4mβNA was purified from germinated Mung bean seeds. Screening of cereals and legumes for DPP-III revealed highest activity in Phaseolus vulgaris and Vigna radiata (variety P.9531) seeds germinated for 48 h. Homogenate (10%) was acid precipitated upto pH 4.2 and then subjected to 0–55% ammonium sulphate precipitation followed by successive chromatographies on cation exchanger, gel filtration and anion exchanger. Enzyme purity was confirmed by native polyacrylamide gel electrophoresis and in situ gel assays. DPP-III is a heterodimer of ～60 kDa with two subunits of 32.8 kDa and 27 kDa on SDS-PAGE. DPP-III worked optimally at pH 8.0 and at 37 °C with pH stability between 7.5 to 9.5. Arg-Arg-4mβNA was preferred substrate and none of endopeptidase and monopeptidase substrates were hydrolysed. Inhibitors studies revealed it as thiol protease with involvement of metals at active site. The enzyme might be involved in plant's development by generating/deactivating bioactive peptides. Further studies on functional characterization and molecular structure are in progress in our laboratory.     

Purification,kinetic and functional characterization of membrane bound dipeptidyl peptidase-III from NCDC 252: a probiotic lactic acid bacteria

Molecular Biology Reports - Pediococcus acidilactici is a probiotic lactic acid bacteria possessing studied in-vitro probiotic properties. Study of membrane proteins is crucial in developing...     

Membrane Bound Aminopeptidase B of a Potential Probiotic Pediococcus acidilactici NCDC 252: Purification,Physicochemical and Kinetic Characterization

International Journal of Peptide Research and Therapeutics - An arginine aminopeptidase (EC 3.4.11.6) called aminopeptidase B was purified to apparent homogeneity from membrane extract of a...