title: Characterization of an aminopeptidase and a proline iminopeptidase from cabbage leaves.
abstract: Aminopeptidase, preferring phenylalanine-p-nitroanilide as substrate, and proline iminopeptidase, highly-specific for proline-p-nitroanilide, were isolated from cabbage leaves (Brassica oleraceae var. capitata). As pH optima, 7.2-7.5 for aminopeptidase activity and 8.0-8.5 for proline iminopeptidase were determined. Both peptidases were strongly inhibited by p-chloromercuribenzoic acid, heavy metal ions and urea. The molecular weights were determined by gel filtration to be 56 and 204 kDa, respectively. The iminopeptidase was decomposed during SDS electrophoresis to four subunits of 50 kDa. Minor impurities of myrosinase-associated protein (approximately 70 kDa) were found in both preparations. Preliminary data of their amino acid sequences showed similarities to those of aminopeptidases N (family M1) and proline iminopeptidases (family S33).
authors.affiliation: Institute of Organic Chemistry with Centre of Phytochemistry, Acad. G. Bonchev Str. 9, 1113 Sofia, Bulgaria.
authors.forename: Margarita
authors.initials: M
authors.lastname: Marinova
authors.forename: Alexander
authors.initials: A
authors.lastname: Dolashki
authors.forename: Florian
authors.initials: F
authors.lastname: Altenberend
authors.forename: Stefan
authors.initials: S
authors.lastname: Stevanovic
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Voelter
authors.forename: Bozhidar
authors.initials: B
authors.lastname: Tchorbanov
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001937:Brassica / Q000201:enzymology*; D017124:Conserved Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D010446:Peptide Fragments / Q000737:chemistry; D018515:Plant Leaves / Q000201:enzymology*; D016415:Sequence Alignment; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010446:Peptide Fragments; D000626:Aminopeptidases; C022450:prolyl aminopeptidase