Biochemical and ecological characterization of two peroxidase isoenzymes from the mangrove, Rhizophora mangle

Ian S. Pearse, Katy D. Heath, John M. Cheeseman

Research output: Contribution to journalArticlepeer-review


This study examines phenolic peroxidase (POX) in Rhizophora mangle L. leaves in order to assess its role in phenolic manipulation and H 2O2 scavenging. Sun-exposed and understorey leaves experiencing varying degrees of nutrient stress were analysed from an oligotrophic cay off the coast of Belize. POX activity was unaffected by growth environment, but increased throughout leaf development and persisted through senescence and after abscission. Histochemical analyses indicated POX activity throughout leaf tissues, especially in the apoplast. Phenolics were similarly broadly distributed. Two isoenzymes of POX were partially characterized with pIs of 4.1 and 6.3 and masses of 65.5 and 54.3 kDa, respectively. The larger, more acidic isoenzyme showed especially high heat stability, showing no reduced activity after 24 h at 60°C. Rhizophora mangle POX oxidized quercetin preferentially, and, to a lesser extent, coniferyl alcohol, caffeic acid, chlorogenic acid, and p-coumaric acid. It did not oxidize ascorbate, but ascorbate could act as a secondary electron donor in the presence of a phenolic substrate and H2O2. However, because quercetin and other aglycones were not present in R. mangle leaves, and because POX showed no activity with the most abundant leaf flavonoid, rutin, it was concluded that detoxification of H2O2 is secondary to the other roles of POX in manipulation of phenolics.

Original languageEnglish (US)
Pages (from-to)612-622
Number of pages11
JournalPlant, Cell and Environment
Issue number5
StatePublished - May 2005


  • Belize
  • Hydrogen peroxide
  • Photoprotection
  • Red mangrove
  • Rhizophoraceae

ASJC Scopus subject areas

  • Physiology
  • Plant Science


Dive into the research topics of 'Biochemical and ecological characterization of two peroxidase isoenzymes from the mangrove, Rhizophora mangle'. Together they form a unique fingerprint.

Cite this