Three Polyphenol Oxidases from Red Clover (Trifolium pratense) Differ in Enzymatic Activities and Activation Properties

Polyphenol oxidases (PPOs) oxidize o-diphenols to o-quinones, which cause browning reactions in many wounded fruits, vegetables, and plants including the forage crop red clover (Trifolium pratense L.). Production of o-quinones in red clover inhibits postharvest proteolysis during the ensiling proces...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2008-01, Vol.56 (1), p.272-280
Main Authors: Schmitz, George E, Sullivan, Michael L, Hatfield, Ronald D
Format: Article
Language:English
Subjects:
alfalfa
Biological and medical sciences
catechol oxidase
Catechol Oxidase - genetics
Catechol Oxidase - metabolism
complementary DNA
enzymatic activities
Enzyme Activation
enzyme activity
Food Chem/Biochem
Food industries
Fundamental and applied biological sciences. Psychology
Gene Expression
heat stability
Hydrogen-Ion Concentration
Medicago sativa
Medicago sativa - genetics
molecular weight
monophenol monooxygenase
o-diphenols
phenols
plant extracts
Plant Leaves - enzymology
Plants, Genetically Modified - enzymology
Polyphenol oxidase
red clover
Substrate Specificity
transgenic plants
Trifolium - enzymology
Trifolium pratense
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Summary:Polyphenol oxidases (PPOs) oxidize o-diphenols to o-quinones, which cause browning reactions in many wounded fruits, vegetables, and plants including the forage crop red clover (Trifolium pratense L.). Production of o-quinones in red clover inhibits postharvest proteolysis during the ensiling process. The cDNAs encoding three red clover PPOs were expressed individually in alfalfa (Medicago sativa L.), which lacks detectable endogenous foliar PPO activity and o-diphenols. Several physical and biochemical characteristics of the red clover PPOs in alfalfa extracts were determined. In transgenic alfalfa extracts, red clover PPOs exist in a latent state and are activated (10−40-fold increase in activity) by long incubations (>2 days) at ambient temperature or short incubations (
ISSN:0021-8561
1520-5118
DOI:10.1021/jf072488u