Abstract
Spinach glycolate oxidase was subjected to a series of chemical modifications aimed at identifying amino acid residues essential for catalytic activity. The oxidase was reversibly inactivated by treatment with pyridoxal 5'-phosphate (PLP). The inactivation by PLP was accompanied by the appearance of an absorption peak of around 430 nm, which was shifted to 325 nm upon reduction with . After reduction, the PLP-treated oxidase showed a fluorescence spectrum with a maximum of around 395 nm by exciting at 325 nm. The substrate-competitive inhibitors oxalate and oxaloacetate provided protection against inactivation of the oxidase by PLP. These results suggest that PLP inactivates the enzyme by fonning a Schiff base with lysyl residue(s) at an active site of the oxidase. The enzyme was also inactivated by tryptophan-specific reagent N-bromosuccinimide (NBS). However, competitive inhibitors oxalate and oxaloacetate could not protect the oxidase significantly against inactivation of the enzyme by NBS. The results implicate that the inactivation of the oxidase by NBS is not directly related to modification of the tryptophanyl residue at an active site of the enzyme. Treatments of the oxidase with cysteine-specific reagents iodoacetate, silver nitrate, and 5,5'-dithiobis-2-nitrobenzoic acid did not affect significantly the activity of the enzyme.
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Claims 9
Claim · model-written summary
PLP reversibly inactivated spinach glycolate oxidase.
- Taxon
- Spinach
Spinacia oleraceat0 - Treatment
- pyridoxal 5'-phosphate (PLP)e0
- Gene
- glycolate oxidaset0
- Outcome
- oxidasee0
- Direction
- inactivatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The oxidase was reversibly inactivated by treatment with pyridoxal 5'-phosphate (PLP)”
t0“Spinach glycolate oxidase”
Claim · model-written summary
PLP inactivation was accompanied by an absorption peak near 430 nm that shifted to 325 nm upon reduction.
- Taxon
- SpinachSpinacia oleraceat0
- Gene
- glycolate oxidaset0
- Outcome
- absorption peake0
- Direction
- shiftede0
- Value
- around 430 nme0
- Qualifier
- 325 nme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inactivation by PLP was accompanied by the appearance of an absorption peak of around 430 nm, which was shifted to 325 nm upon reduction with .”
t0“Spinach glycolate oxidase”
Claim · model-written summary
Reduced PLP treated oxidase fluoresced maximally around 395 nm upon excitation at 325 nm.
- Taxon
- SpinachSpinacia oleraceat0
- Gene
- glycolate oxidaset0
- Outcome
- fluorescence spectrume0
- Value
- around 395 nme0
- Qualifier
- exciting at 325 nme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After reduction, the PLP-treated oxidase showed a fluorescence spectrum with a maximum of around 395 nm by exciting at 325 nm”
t0“Spinach glycolate oxidase”
Claim · model-written summary
Oxalate and oxaloacetate protected the oxidase against PLP inactivation.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- oxalate and oxaloacetatee0
- Gene
- glycolate oxidaset0
- Outcome
- inactivation of the oxidase by PLPe0
- Direction
- protectione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The substrate-competitive inhibitors oxalate and oxaloacetate provided protection against inactivation of the oxidase by PLP”
t0“Spinach glycolate oxidase”
Claim · model-written summary
PLP may inactivate the oxidase by forming a Schiff base with active site lysyl residues.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- PLPe0
- Gene
- glycolate oxidaset0
- Outcome
- inactivates the enzymee0
- Qualifier
- Schiff base with lysyl residue(s)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PLP inactivates the enzyme by fonning a Schiff base with lysyl residue(s) at an active site of the oxidase”
t0“Spinach glycolate oxidase”
Claim · model-written summary
NBS inactivated the oxidase.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- N-bromosuccinimide (NBS)e0
- Gene
- glycolate oxidaset0
- Outcome
- enzymee0
- Direction
- inactivatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The enzyme was also inactivated by tryptophan-specific reagent N-bromosuccinimide (NBS)”
t0“Spinach glycolate oxidase”
Claim · model-written summary
Oxalate and oxaloacetate did not significantly protect against NBS inactivation.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- oxalate and oxaloacetatee0
- Gene
- glycolate oxidaset0
- Outcome
- inactivation of the enzyme by NBSe0
- Direction
- could not protecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“competitive inhibitors oxalate and oxaloacetate could not protect the oxidase significantly against inactivation of the enzyme by NBS”
t0“Spinach glycolate oxidase”
Claim · model-written summary
NBS inactivation was inferred not to depend directly on active site tryptophan modification.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- NBSe0
- Gene
- glycolate oxidaset0
- Outcome
- inactivation of the oxidasee0
- Qualifier
- modification of the tryptophanyl residue at an active sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the inactivation of the oxidase by NBS is not directly related to modification of the tryptophanyl residue at an active site of the enzyme”
t0“Spinach glycolate oxidase”
Claim · model-written summary
Cysteine specific reagents did not significantly affect oxidase activity.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- cysteine-specific reagents iodoacetate, silver nitrate, and 5,5'-dithiobis-2-nitrobenzoic acide0
- Gene
- glycolate oxidaset0
- Outcome
- activity of the enzymee0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatments of the oxidase with cysteine-specific reagents iodoacetate, silver nitrate, and 5,5'-dithiobis-2-nitrobenzoic acid did not affect significantly the activity of the enzyme”
t0“Spinach glycolate oxidase”
The same questions in other papers
reagent · physiology: enzyme activity · Spinacia oleracea (spinach)Positive and negative results
1 in the opposite direction
- positive
oxalate · molecular: metabolites · Spinacia oleracea (spinach)Positive and negative results
2 in the opposite direction
- negative
- negative
oxaloacetate(2-) · molecular: metabolites · Spinacia oleracea (spinach)Results agree
1 paper in the same direction as this paper
- positive
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.