Abstract
Shikimate kinase was purified to near homogenity from spinach Spinacia oleracea L. chloroplasts and found to consist of a single 31 kilodalton polypeptide. The purified enzyme was unstable, but could be stabilized by a variety of added proteins, including oxidized and reduced thioredoxins. Whereas the isolated enzyme was stimulated by mono- and dithiol reagents, the enzyme in intact chloroplasts was unaffected by added thiols and showed only minor response to dark/light transitions. These results indicate that the previously reported stimulation of shikimate kinase activity by reduced thioredoxins is due to enzyme stabilization rather than to activation. In the current study, the purified enzyme was inhibited by added ADP and showed a strong response to energy charge. When intact chloroplasts were incubated in the dark in presence of shikimate, phosphoenolpyruvate and a source of ATP (dihydroxyacetone phosphate or ATP itself under appropriate conditions), aromatic amino acids were formed: phenylalanine and tyrosine. The data indicate that energy charge plays a role in regulating shikimate kinase, thereby controlling the shikimate pathway. An unidentified enzyme of the latter part of the pathway, leading from shikimate-3-phosphate to phenylalanine, appears to be activated by light.
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Claims 11
Claim · model-written summary
Purified spinach shikimate kinase consisted of one 31 kilodalton polypeptide.
- Taxon
- spinach
Spinacia oleraceae0 - Organ / stage
- chloroplastse0
- Gene
- Shikimate kinasee0
- Outcome
- a single 31 kilodalton polypeptidee0
- Value
- 31 kilodaltone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shikimate kinase was purified to near homogenity from spinach Spinacia oleracea L. chloroplasts and found to consist of a single 31 kilodalton polypeptide.”
Claim · model-written summary
Added proteins including thioredoxins stabilized the purified enzyme.
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- oxidized and reduced thioredoxinse0
- Gene
- Shikimate kinaset0
- Outcome
- stabilizede0
- Direction
- stabilizede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The purified enzyme was unstable, but could be stabilized by a variety of added proteins, including oxidized and reduced thioredoxins.”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
Mono- and dithiol reagents stimulated isolated shikimate kinase.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- mono- and dithiol reagentse0
- Gene
- Shikimate Kinaset0
- Outcome
- isolated enzymee0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the isolated enzyme was stimulated by mono- and dithiol reagents”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
Added thiols did not affect shikimate kinase in intact chloroplasts.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- added thiolse0
- Gene
- Shikimate Kinaset0
- Outcome
- the enzyme in intact chloroplastse0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the enzyme in intact chloroplasts was unaffected by added thiols”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
Shikimate kinase in intact chloroplasts responded only slightly to dark/light transitions.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- dark/light transitionse0
- Gene
- Shikimate Kinaset0
- Outcome
- minor responsee0
- Direction
- minor responsee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“showed only minor response to dark/light transitions”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
Reduced thioredoxins appeared to stimulate measured kinase activity by enzyme stabilization rather than activation.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- reduced thioredoxinse0
- Gene
- shikimate kinasee0
- Outcome
- shikimate kinase activitye0
- Qualifier
- enzyme stabilization rather than to activatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulation of shikimate kinase activity by reduced thioredoxins is due to enzyme stabilization rather than to activation”
t0“Spinach”
Claim · model-written summary
Added ADP inhibited the purified enzyme.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- added ADPe0
- Gene
- Shikimate Kinaset0
- Outcome
- purified enzymee0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the purified enzyme was inhibited by added ADP”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
The purified enzyme responded strongly to energy charge.
- Taxon
- SpinachSpinacia oleraceat0
- Gene
- Shikimate Kinaset0
- Compound
- energy chargee0
- Outcome
- strong responsee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“showed a strong response to energy charge”
t0“Shikimate Kinase from Spinach Chloroplasts”
Claim · model-written summary
Dark-incubated chloroplasts formed phenylalanine and tyrosine with shikimate, phosphoenolpyruvate, and ATP supply.
- Taxon
- SpinachSpinacia oleraceat0
- Organ / stage
- chloroplastse0
- Treatment
- shikimate, phosphoenolpyruvate and a source of ATPe0
- Outcome
- phenylalanine and tyrosinee0
- Direction
- formede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When intact chloroplasts were incubated in the dark in presence of shikimate, phosphoenolpyruvate and a source of ATP (dihydroxyacetone phosphate or ATP itself under appropriate conditions), aromatic amino acids were formed: phenylalanine and tyrosine.”
t0“Spinach”
Claim · model-written summary
Energy charge regulates shikimate kinase and thereby the shikimate pathway.
- Taxon
- SpinachSpinacia oleraceat0
- Gene
- shikimate kinasee0
- Compound
- energy chargee0
- Outcome
- shikimate pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy charge plays a role in regulating shikimate kinase, thereby controlling the shikimate pathway”
t0“Spinach”
Claim · model-written summary
Light apparently activates an unidentified late shikimate-pathway enzyme.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- lighte0
- Gene
- unidentified enzymee0
- Outcome
- appears to be activatede0
- Qualifier
- leading from shikimate-3-phosphate to phenylalaninee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An unidentified enzyme of the latter part of the pathway, leading from shikimate-3-phosphate to phenylalanine, appears to be activated by light.”
t0“Spinach”
The same questions in other papers
phosphoenolpyruvate · molecular: metabolites · Spinacia oleracea (spinach)Positive and negative results
1 in the opposite direction
- negative
reagent · physiology: enzyme activity · Spinacia oleracea (spinach)Positive and negative results
1 in the opposite direction
- no effect
ATP · molecular: metabolites · Spinacia oleracea (spinach)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- no effect
- no effect
- 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.