Characterization of peroxidase in buckwheat seed

Phytochemistry. 2006 Feb;67(3):219-24. doi: 10.1016/j.phytochem.2005.11.014. Epub 2006 Jan 3.

Abstract

A peroxidase (POX)-containing fraction was purified from buckwheat seed. The POX consisted of two isozymes, POX I and POX II, that were purified 6.6- and 67.4-fold, respectively. Their molecular weights were estimated to be 46.1 kDa (POX I) and 58.1 kDa (POX II) by gel filtration. While POX I and II each oxidized quercetin, o-dianisidine, ascorbic acid and guaiacol, only POX II oxidized ABTS. Kinetic studies revealed that POX I and II had lower K(m) values for quercetin (0.071 and 0.028 mM), ABTS (0.016 mM for POX II) and ascorbic acid (0.043 and 0.029 mM) than for o-dianisidine (0.229 and 0.137 mM) and guaiacol (0.288 and 0 ). The optimum pHs of POX I and II for various substrates were almost the same, except for quercetin; pH 8.0 for POX I and pH 4.5 for II. Their optimal temperatures were 30 degrees C (POX I) and 10 degrees C (POX II), and POX I was more stable than POX II above 30 degrees C.

MeSH terms

  • Ascorbic Acid / chemistry
  • Ascorbic Acid / metabolism
  • Benzothiazoles
  • Dianisidine / chemistry
  • Dianisidine / metabolism
  • Enzyme Stability
  • Fagopyrum / enzymology*
  • Guaiacol / chemistry
  • Guaiacol / metabolism
  • Hydrogen-Ion Concentration
  • Isoenzymes / chemistry
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism
  • Kinetics
  • Peroxidase / chemistry*
  • Peroxidase / isolation & purification
  • Peroxidase / metabolism
  • Quercetin / chemistry
  • Quercetin / metabolism
  • Seeds / enzymology
  • Sulfonic Acids / chemistry
  • Sulfonic Acids / metabolism
  • Temperature
  • Tissue Distribution

Substances

  • Benzothiazoles
  • Isoenzymes
  • Sulfonic Acids
  • 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid
  • Guaiacol
  • Quercetin
  • Peroxidase
  • Dianisidine
  • Ascorbic Acid