title: Two new cysteine endopeptidases obtained from the latex of Araujia hortorum fruits.
abstract: Two new endopeptidases were purified to homogeneity from the latex of Araujia hortorum fruits by a simple purification procedure involving ultracentrifugation and ion exchange chromatography. Molecular weights of araujiain h II and araujiain h III were 23,718 and 23546 (mass spectrometry), respectively. The isoelectric point of araujiain h II was 8.9, whereas araujiain h III had a pI higher than 9.3. Maximum proteolytic activity on caseine was reached at pH 8.0-9.0 for both endopeptidases, which were irreversibly inhibited by iodoacetate and E-64, suggesting they belong to the cysteine protease family. Esterolytic activity was determined on N-alpha-CBZ-amino acid-p-nitrophenyl esters, and the highest kcat/Km values for the both enzymes were obtained with the glutamine derivative. The N-terminal sequences of araujiain h II and araujiain h III showed a high degree of homology with other plant cysteine endopeptidases.
authors.affiliation: Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina.
authors.forename: W D
authors.initials: WD
authors.lastname: Obregón
authors.forename: M C
authors.initials: MC
authors.lastname: Arribére
authors.forename: S M
authors.initials: SM
authors.lastname: del Valle
authors.forename: C
authors.initials: C
authors.lastname: Liggieri
authors.forename: N
authors.initials: N
authors.lastname: Caffini
authors.forename: N
authors.initials: N
authors.lastname: Priolo
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005638:Fruit / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007700:Kinetics; D007840:Latex / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010946:Plants, Medicinal / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D014461:Ultracentrifugation
chemical_list: D007840:Latex; D003546:Cysteine Endopeptidases