Metabolites of 2,3-diketogulonate delay peroxidase action and induce non-enzymic H2O2 generation : Potential roles in the plant cell wall

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Karkonen , A , Dewhirst , R A , Mackay , C L & Fry , S C 2017 , ' Metabolites of 2,3-diketogulonate delay peroxidase action and induce non-enzymic H2O2 generation : Potential roles in the plant cell wall ' , Archives of Biochemistry and Biophysics , vol. 620 , pp. 12-22 . https://doi.org/10.1016/j.abb.2017.03.006

Title: Metabolites of 2,3-diketogulonate delay peroxidase action and induce non-enzymic H2O2 generation : Potential roles in the plant cell wall
Author: Karkonen, Anna; Dewhirst, Rebecca A.; Mackay, C. Logan; Fry, Stephen C.
Contributor organization: Department of Agricultural Sciences
Date: 2017-04-15
Language: eng
Number of pages: 11
Belongs to series: Archives of Biochemistry and Biophysics
ISSN: 0003-9861
DOI: https://doi.org/10.1016/j.abb.2017.03.006
URI: http://hdl.handle.net/10138/185243
Abstract: A proportion of the plant's L-ascorbate (vitamin C) occurs in the apoplast, where it and its metabolitesmay act as pro-oxidants and anti-oxidants. One ascorbate metabolite is 2,3-dilcetogulonate (DKG), preparations of which can non-enzymically generate H2O2 and delay peroxidase action on aromatic substrates. As DKG itself generates several by-products, we characterised these and their ability to generate H2O2 and delay peroxidase action. DKG preparations rapidly produced a by-product, compound (1), with lambda(max) 271 and 251 nm at neutral and acidic pH respectively. On HPLC, (1) co-eluted with the major H2O2-generating and peroxidase-delaying principle. Compound (1) was slowly destroyed by ascorbate oxidase, and was less stable at pH 6 than at pH 1. Electrophoresis of an HPLC-enriched preparation of (1) suggested a strongly acidic (pK(a) approximate to 2.3) compound. Mass spectrometry suggested that un-ionised (1) has the formula C6H6O5, i.e. it is a reduction product of DKG (C6H8O7). In conclusion, compound (1) is the major H2O2-generating, peroxidase-delaying principle formed non-enzymically from DKG in the pathway ascorbate -> dehydroascorbic acid -> DKG -> (1). We hypothesise that (1) generates apoplastic H2O2 (and consequently hydroxyl radicals) and delays cell-wall crosslinking - both these effects favouring wall loosening, and possibly playing a role in pathogen defence. (C) 2017 The Authors. Published by Elsevier Inc.
Subject: Ascorbate
Dehydroascorbic acid
Diketogulonate
Apoplast
Peroxidase
Hydrogen peroxide
Hydroxyl radical
Plant cell wall
L-ASCORBIC-ACID
PERFORMANCE LIQUID-CHROMATOGRAPHY
VITAMIN-C DEGRADATION
DEHYDROASCORBIC ACID
APOPLASTIC ASCORBATE
HYDROXYL RADICALS
2,3-DIKETO-L-GULONIC ACID
TRANSFORMATION PRODUCTS
OXIDATIVE-DEGRADATION
ARABIDOPSIS-THALIANA
1183 Plant biology, microbiology, virology
415 Other agricultural sciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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