title: Purification, cloning and characterization of a novel peroxidase isozyme from sweetpotatoes (Ipomoea batatas).
abstract: An anionic peroxidase from sweetpotato tubers is purified and characterized. The isozyme ibPrx15 is purified to homogeneity by affinity chromatography using a concanavalin A column. The isoelectric point was determined to pI 4.9. MALDI-MS detected a singly charged molecule with a mass of 42029 Da. Absorption spectra of ibPrx15 compounds I, II and III were obtained after treatment with H(2)O(2) at room temperature. Comparative data of ibPrx15 on substrate specificity to tobacco anionic peroxidase (TOP) and horseradish peroxidase (HRP) reveal similar specific activity towards a series of conventional substrates except for iodide, which is a two-electron donor interacting directly with the compound I derivative in the catalytic cycle. ibPrx15 exhibits a high specific activity towards iodide about 10(3)-fold to that of tobacco peroxidase. The amino acid sequence of the main isozyme ibPrx15 was determined by Edman degradation and by sequencing the amplified cDNA fragments. ibPrx15 has 86% identity to another Ipomoea sequence ibPrx05 and 72% identity with a sequence from Populus trichocarpa (PtPrx72).
authors.affiliation: Institut für Biochemie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Strasse 2, D-48149 Münster, Germany. romela@uni-muenster.de
authors.forename: Annette
authors.initials: A
authors.lastname: Rompel
authors.forename: Michael
authors.initials: M
authors.lastname: Albers
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Naseri
authors.forename: Carsten
authors.initials: C
authors.lastname: Gerdemann
authors.forename: Klaudia
authors.initials: K
authors.lastname: Büldt-Karentzopoulos
authors.forename: Beate
authors.initials: B
authors.lastname: Jasper
authors.forename: Bernt
authors.initials: B
authors.lastname: Krebs
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D027723:Ipomoea batatas / Q000201:enzymology* / Q000235:genetics; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D009195:Peroxidase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D017385:Sequence Homology
chemical_list: D007527:Isoenzymes; D009195:Peroxidase