Abstract
The role of the conserved glutamic acid residue in anionic plant peroxidases with regard to substrate specificity and stability was examined. A Glu141Phe substitution was generated in tobacco anionic peroxidase (TOP) to mimic neutral plant peroxidases such as horseradish peroxidase C (HRP C). The newly constructed enzyme was compared to wild-type recombinant TOP and HRP C expressed in E. coli. The Glu141Phe substitution supports heme entrapment during the refolding procedure and increases the reactivation yield to 30% compared to 7% for wild-type TOP. The mutation reduces the activity towards ABTS, o-phenylenediamine, guaiacol and ferrocyanide to 50% of the wild-type activity. No changes are observed with respect to activity for the lignin precursor substrates, coumaric and ferulic acid. The Glu141Phe mutation destabilizes the enzyme upon storage and against radical inactivation, mimicking inactivation in the reaction course. Structural alignment shows that Glu141 in TOP is likely to be hydrogen-bonded to Gln149, similar to the Glu143-Lys151 bond in Arabidopsis A2 peroxidase. Supposedly, the Glu141-Gln149 bond provides TOP with two different modes of stabilization: (1) it prevents heme dissociation, i.e., it 'guards' heme inside the active center; and (2) it constitutes a shield to protect the active center from solvent-derived radicals.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 7
Claim · model-written summary
Glu141Phe raised peroxidase reactivation yield to 30% versus 7% for wild type.
- Taxon
- tobacco
Nicotiana tabacumt0 - Treatment
- Glu141Phe substitutione0
- Gene
- Glu141Phee0
- Outcome
- reactivation yielde0
- Direction
- increasese0
- Value
- 30%e0
- Qualifier
- 7%e0
- Comparator
- wild-type TOPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“The Glu141Phe substitution supports heme entrapment during the refolding procedure and increases the reactivation yield to 30% compared to 7% for wild-type TOP.”
Claim · model-written summary
Glu141Phe supported heme entrapment during refolding.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Glu141Phe substitutione0
- Gene
- Glu141Phee0
- Outcome
- heme entrapmente0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“The Glu141Phe substitution supports heme entrapment during the refolding procedure”
Claim · model-written summary
Glu141Phe reduced activity toward four substrates to half of wild type.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- mutatione0
- Outcome
- activity towards ABTS, o-phenylenediamine, guaiacol and ferrocyanidee0
- Direction
- reducese0
- Value
- 50%e0
- Comparator
- wild-typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“The mutation reduces the activity towards ABTS, o-phenylenediamine, guaiacol and ferrocyanide to 50% of the wild-type activity.”
Claim · model-written summary
Activity toward coumaric and ferulic acid did not change.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Glu141Phe mutatione1
- Outcome
- activity for the lignin precursor substrates, coumaric and ferulic acide0
- Direction
- No changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“No changes are observed with respect to activity for the lignin precursor substrates, coumaric and ferulic acid.”
e1“The Glu141Phe mutation destabilizes the enzyme”
Claim · model-written summary
Glu141Phe destabilized the enzyme during storage and against radical inactivation.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Glu141Phe mutatione0
- Outcome
- enzymee0
- Direction
- destabilizese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“The Glu141Phe mutation destabilizes the enzyme upon storage and against radical inactivation”
Claim · model-written summary
Structural alignment suggested a Glu141 to Gln149 hydrogen bond.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- Glu141e0
- Outcome
- likely to be hydrogen-bonded to Gln149e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“Structural alignment shows that Glu141 in TOP is likely to be hydrogen-bonded to Gln149”
Claim · model-written summary
Authors propose that the Glu141-Gln149 bond prevents heme dissociation and shields the active center from radicals.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- Glu141-Gln149e0
- Outcome
- prevents heme dissociatione0
- Qualifier
- shield to protect the active center from solvent-derived radicalse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tobacco”
e0“Supposedly, the Glu141-Gln149 bond provides TOP with two different modes of stabilization: (1) it prevents heme dissociation, i.e., it 'guards' heme inside the active center; and (2) it constitutes a shield to protect the active center from solvent-derived radicals.”
The same questions in other papers
loss of function · molecular: metabolites · Nicotiana tabacum (tobacco)Positive and negative results
13 papers in the same direction as this paper · 10 in the opposite direction
- no effect
- positive
- positive
20 papers more in this group
See all 24 papers →loss of function · physiology: enzyme activity · Nicotiana tabacum (tobacco)Results agree
7 papers in the same direction as this paper
- no effect
- no effect
- no effect
4 papers more in this group
See all 8 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.