Kinetic Characterization of the Oxidation of Chlorogenic Acid by Polyphenol Oxidase and Peroxidase. Characteristics of the o-Quinone
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- 作者：J. Muñ ; oz ; F. Garcia-Molina ; R. Varon ; J. N. Rodriguez-Lopez ; P. A. Garcí ; a-Ruiz ; F. Garcí ; a-Cá ; novas ; J. Tudela
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2007
- 出版时间：February 7, 2007
- 年：2007
- 卷：55
- 期：3
- 页码：920 - 928
- 全文大小：198K
- 年卷期：v.55,no.3(February 7, 2007)
- ISSN：1520-5118
文摘
Chlorogenic acid is the major diphenol of many fruits, where it is oxidized enzymatically by polyphenoloxidase (PPO) or peroxidase (POD) to its o-quinone. In spectrophotometric studies of chlorogenicacid oxidation with a periodate ratio of [CGA]0/[IO4-]0 < 1 and [CGA]0/[IO4-]0 > 1, the o-quinone wascharacterized as follows: 
max at 400 nm and 
= 2000 and 2200 M-1 cm-1 at pH 4.5 and 7.0,respectively. In studies of o-quinone generated by the oxidation of chlorogenic acid using a periodateat ratio of [CGA]0/[IO4-]0 > 1, a reaction with the remaining substrate was detected, showing rateconstants of k = 2.73 ± 0.17 M-1 s-1 and k' = 0.05 ± 0.01 M-1 s-1 at the above pH values. Achronometric spectrophotometric method is proposed to kinetically characterize the action of the PPOor POD on the basis of measuring the time it takes for a given amount of ascorbic acid to be consumedin the reaction with the o-quinone. The kinetic constants of mushroom PPO and horseradish PODare determined.
max at 400 nm and = 2000 and 2200 M-1 cm-1 at pH 4.5 and 7.0,respectively. In studies of o-quinone generated by the oxidation of chlorogenic acid using a periodateat ratio of [CGA]0/[IO4-]0 > 1, a reaction with the remaining substrate was detected, showing rateconstants of k = 2.73 ± 0.17 M-1 s-1 and k' = 0.05 ± 0.01 M-1 s-1 at the above pH values. Achronometric spectrophotometric method is proposed to kinetically characterize the action of the PPOor POD on the basis of measuring the time it takes for a given amount of ascorbic acid to be consumedin the reaction with the o-quinone. The kinetic constants of mushroom PPO and horseradish PODare determined.