Ascorbate peroxidase in tea [Camellia sinensis] leaves: Occurrence of two isozymes and the differences in their enzymatic and molecular properties

Two isozymes of ascorbate (AsA) peroxidase were found in tea leaves, and one of them (AsA peroxidase II) was purified to homogeneity, as judged by polyacrylamide gel electrophoresis. AsA peroxidase II is a monomer with a molecular weight of 34,000 and contains protoheme, but it is not a glycoprotein...

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Bibliographic Details
Published in:Plant and cell physiology 1989-10, Vol.30 (7), p.987-998
Main Authors: Chen, G.X. (Kyoto Univ., Uji (Japan). Research Inst. for Food Science), Asada, K
Format: Article
Language:English
Subjects:
ACIDE ASCORBIQUE
ACIDO ASCORBICO
Analytical, structural and metabolic biochemistry
Ascorbate peroxidase
ASCORBIC ACID
Biological and medical sciences
CAMELLIA SINENSIS
Chloroplast
Enzymes and enzyme inhibitors
Fundamental and applied biological sciences. Psychology
Hydrogen peroxide
ISOENZIMAS
ISOENZYME
ISOENZYMES
Isozyme
leaves
MOLECULAR WEIGHT
Oxidoreductases
PEROXIDASAS
PEROXIDASES
PEROXYDASE
PESO MOLECULAR
POIDS MOLECULAIRE
Scavenger
Tea (Camellia sinensis)
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Summary:Two isozymes of ascorbate (AsA) peroxidase were found in tea leaves, and one of them (AsA peroxidase II) was purified to homogeneity, as judged by polyacrylamide gel electrophoresis. AsA peroxidase II is a monomer with a molecular weight of 34,000 and contains protoheme, but it is not a glycoprotein. The enzyme showed a Soret peak at 409 run and at 420 nm when oxidized and reduced, respectively, with an a-band at 556 nm. The oxidized enzyme showed two small peaks at 478 nm and 530 nm. The peak at 478 nm disappeared when the enzyme was inactivated by depletion of AsA or by the addition of cyanide. Antibody raised against AsA peroxidase II from tea did not cross-react with guaiacol peroxidase from spinach, and antibody against the guaiacol peroxidase did not with AsA peroxidases from tea leaf. The amino acid composition and amino acid sequence of the amino-terminal region of AsA peroxidase II were determined. Little homology in terms of amino acid sequence was found between AsA peroxidase II and various guaiacol peroxidases. The enzymatic and molecular properties of the two isozymes showed distinct differences with respect to molecular weight, sensitivity to AsA-depletion, specificity for the electron donor, and other enzymatic properties.
ISSN:0032-0781
1471-9053
1471-9053
0032-0781
DOI:10.1093/oxfordjournals.pcp.a077844