Understanding functional diversity and substrate specificity in haem peroxidases: what can we learn from ascorbate peroxidase?

Raven, Emma Lloyd

doi:10.1039/b210426c

Cited by 66 publications

(18 citation statements)

References 185 publications

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“…One-electron donation from ascorbate (which can in principle act as either a 1-or 2-e − donor) is the observed pathway in plant peroxidases; semidehydroascorbate is thought to dimerize over time. 39, 40 Following mixing with 1 eq of ascorbate, a species consistent with Compound II, the expected 1-e − reduction product, forms (Soret band at 412 nm; α/β = 525, 555 nm). This species persists for several minutes with concurrent, gradual bleaching of the chromophore.…”

Section: Resultsmentioning

confidence: 99%

Peroxidase-Type Reactions Suggest a Heterolytic/Nucleophilic O–O Joining Mechanism in the Heme-Dependent Chlorite Dismutase

et al. 2013

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Heme-containing chlorite dismutases (Clds) catalyze a highly unusual O–O bond forming reaction. The O–O cleaving reactions of hydrogen peroxide and peracetic acid (PAA) with the Cld from Dechloromonas aromatica (DaCld) were studied to better understand the Cl–O cleavage of the natural substrate and subsequent O–O bond formation. While reactions with H2O2 resulted in slow destruction of the heme, at acidic pH, heterolytic cleavage of the O–O bond of PAA cleanly yielded the ferryl porphyrin cation radical (Compound I). At alkaline pH, the reaction proceeds more rapidly and the first observed intermediate is a ferryl heme. Freezequench EPR confirmed that the latter has an uncoupled protein-based radical, indicating that Compound I is the first intermediate formed at all pH values and that radical migration is faster at alkaline pH. These results suggest by analogy that two-electron Cl–O bond cleavage to yield a ferryl-porphyrin cation radical is the most likely initial step in O–O bond formation from chlorite.

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Section: Resultsmentioning

confidence: 99%

Peroxidase-Type Reactions Suggest a Heterolytic/Nucleophilic O–O Joining Mechanism in the Heme-Dependent Chlorite Dismutase

et al. 2013

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“…Regarding the heme binding site, in Physcomitrella tAPx and Chamydomonas sAPx position R 282 is replaced by a H, like it is in many cytosolic APx [49]. All other amino acids important for heme binding (P 133 , P 238 , L 272 , H 276 , L 278 , G 279 , R 280 , S 286 , and Y 372 ) [4,51] (labeled "H" in Fig. 1A) are conserved within the examined species.…”

Section: Resultsmentioning

confidence: 99%

“…1A) [4,49,51] are widely conserved like several unspecified residues (e.g. L 138 , G 144 , T 145 , Y 146 , K 148 , I 150 , E 152 , W 153 , P 154 ).…”

Section: Resultsmentioning

confidence: 99%

“…H 2 O 2 is scavenged by low molecular weight antioxidants, such as ascorbate and glutathione [1]. More efficiently, it is enzymatically inactivated by peroxidases [2-4]. Inside chloroplasts, the main peroxidases are ascorbate peroxidases (APx), peroxiredoxins (Prx) and glutathione peroxidases (GPx) [2-5].…”

Section: Introductionmentioning

confidence: 99%

“…The targeting signal is encoded in a N-terminal transit peptide [20-22]. The chloroplast isoforms of APx, GPx and PrxII have cytosolic counterparts [4,13,17,23], while in higher plants 2CP and PrxQ are exclusively found in chloroplasts [19,21]. Plant GPx show a high sequence similarity to animal GPx4, suggesting an eukaryotic origin [17].…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the chloroplast peroxidase system in the chlorophyte Chlamydomonas reinhardtii, the bryophyte Physcomitrella patens, the lycophyte Selaginella moellendorffii and the seed plant Arabidopsis thaliana

2010

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BackgroundOxygenic photosynthesis is accompanied by the formation of reactive oxygen species (ROS), which damage proteins, lipids, DNA and finally limit plant yield. The enzymes of the chloroplast antioxidant system are exclusively nuclear encoded. During evolution, plastid and mitochondrial genes were post-endosymbiotically transferred to the nucleus, adapted for eukaryotic gene expression and post-translational protein targeting and supplemented with genes of eukaryotic origin.ResultsHere, the genomes of the green alga Chlamydomonas reinhardtii, the moss Physcomitrella patens, the lycophyte Selaginella moellendorffii and the seed plant Arabidopsis thaliana were screened for ORFs encoding chloroplast peroxidases. The identified genes were compared for their amino acid sequence similarities and gene structures. Stromal and thylakoid-bound ascorbate peroxidases (APx) share common splice sites demonstrating that they evolved from a common ancestral gene. In contrast to most cormophytes, our results predict that chloroplast APx activity is restricted to the stroma in Chlamydomonas and to thylakoids in Physcomitrella. The moss gene is of retrotransposonal origin.The exon-intron-structures of 2CP genes differ between chlorophytes and streptophytes indicating an independent evolution. According to amino acid sequence characteristics only the A-isoform of Chlamydomonas 2CP may be functionally equivalent to streptophyte 2CP, while the weakly expressed B- and C-isoforms show chlorophyte specific surfaces and amino acid sequence characteristics. The amino acid sequences of chloroplast PrxII are widely conserved between the investigated species. In the analyzed streptophytes, the genes are unspliced, but accumulated four introns in Chlamydomonas. A conserved splice site indicates also a common origin of chlorobiont PrxQ.The similarity of splice sites also demonstrates that streptophyte glutathione peroxidases (GPx) are of common origin. Besides a less related cysteine-type GPx, Chlamydomonas encodes two selenocysteine-type GPx. The latter were lost prior or during streptophyte evolution.ConclusionThroughout plant evolution, there was a strong selective pressure on maintaining the activity of all three investigated types of peroxidases in chloroplasts. APx evolved from a gene, which dates back to times before differentiation of chlorobionts into chlorophytes and streptophytes, while Prx and presumably also GPx gene patterns may have evolved independently in the streptophyte and chlorophyte branches.

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Ascorbate Peroxidase

and¹,

Poulos²

2005

Antioxidants and Reactive Oxygen Species in Plants

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Understanding functional diversity and substrate specificity in haem peroxidases: what can we learn from ascorbate peroxidase?

Cited by 66 publications

References 185 publications

Peroxidase-Type Reactions Suggest a Heterolytic/Nucleophilic O–O Joining Mechanism in the Heme-Dependent Chlorite Dismutase

Peroxidase-Type Reactions Suggest a Heterolytic/Nucleophilic O–O Joining Mechanism in the Heme-Dependent Chlorite Dismutase

Comparison of the chloroplast peroxidase system in the chlorophyte Chlamydomonas reinhardtii, the bryophyte Physcomitrella patens, the lycophyte Selaginella moellendorffii and the seed plant Arabidopsis thaliana

Ascorbate Peroxidase

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