title: Purification and characterisation of an intracellular X-prolyl-dipeptidyl aminopeptidase from Streptococcus thermophilus ACA-DC 4.
abstract: An intracellular X-prolyl-dipeptidyl aminopeptidase from Streptococcus thermophilus ACA-DC 4, isolated from traditional Greek yoghurt, was purified by anion exchange and gel filtration chromatography. A single band of molecular weight of about 80,000 appeared in SDS-PAGE; by gel filtration it was shown that the native enzyme was dimeric. The peptidase showed optimum activity on glycyl-prolyl 4-nitroanilide at pH 7.0 and at 50 degrees C, with K(m) = 3.1 mM and Vmax = 3500 U mg-1; over 50 degrees C the enzyme activity declined rapidly. It was inactivated by PMSF; sulfhydryl group reagents and metal chelators had little effect on enzyme activity.
authors.affiliation: Laboratory of Dairy Research, Agricultural University of Athens, Greece. et@auadec.aua.ariadne-t.gr
authors.forename: E
authors.initials: E
authors.lastname: Tsakalidou
authors.forename: R
authors.initials: R
authors.lastname: Anastasiou
authors.forename: K
authors.initials: K
authors.lastname: Papadimitriou
authors.forename: E
authors.initials: E
authors.lastname: Manolopoulou
authors.forename: G
authors.initials: G
authors.lastname: Kalantzopoulos
mesh_terms: D000813:Anilides / Q000378:metabolism; D002364:Caseins / Q000378:metabolism; D019281:Dimerization; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D011392:Proline / Q000378:metabolism; D011487:Protein Conformation; D013291:Streptococcus / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature; D014105:Tosyl Compounds / Q000494:pharmacology; D015014:Yogurt / Q000382:microbiology*
chemical_list: D000813:Anilides; D002364:Caseins; D004791:Enzyme Inhibitors; D014105:Tosyl Compounds; C003614:4-toluenesulfonyl fluoride; D011392:Proline; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases