Abstract
1. The activity of pyruvate,P(i) dikinase in leaves of maize and Amaranthus palmeri rapidly falls on transferring illuminated plants to darkness. Illumination of dark-treated plants results in an immediate rapid increase in activity of the enzyme, the final activity reached being dependent on the intensity of the incident light. 2. Activation of the enzyme in extracts of dark-treated maize leaves after gel filtration on Sephadex G-25 requires a thiol and P(i). The P(i) requirement for activation can be replaced by arsenate. Activation of the enzyme is inhibited by AMP and GMP and possibly also by ADP and ATP. Activation of the enzyme after gel filtration on Sephadex G-200 also requires a heat-labile component that is excluded by Sephadex G-25. 3. The active enzyme isolated from illuminated leaves is inactivated by ADP in the presence of a thiol, the rate of inactivation being very much faster in air than in an oxygen-free atmosphere. Reactivation of the ADP-inactivated enzyme requires a thiol, P(i) and a component excluded by Sephadex G-25 but considerably retarded by Sephadex G-200. 4. The active enzyme is rapidly and irreversibly inactivated in the absence of a thiol. Inactivation is accelerated by both sodium diethyldithiocarbamate and tetraethylthiuram disulphide, and the enzyme inactivated by these reagents is completely reactivated by incubation with dithiothreitol. This reactivation does not require P(i). The inactive enzyme from dark-treated leaves is stabilized by diethyldithiocarbamate and can be partially activated by dithiothreitol alone; complete reactivation requires both dithiothreitol and P(i). 5. The enzyme activity is markedly inhibited by the thiol reagents p-chloromercuribenzoate, gamma-(p-arsenophenyl)-n-butyrate and an equimolar mixture of arsenite and 2,3-dimercaptopropan-1-ol. 6. The processes of activation and inactivation observed in vitro are discussed in relation to the regulation of pyruvate,P(i) dikinase activity in the leaf.
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Claims 16
Claim · model-written summary
Darkness rapidly lowered leaf pyruvate dikinase activity in maize and Amaranthus palmeri.
- Taxon
- maize and Amaranthus palmeri
Zea mays
Amaranthus palmerie0 - Organ / stage
- leavese0
- Treatment
- darknesse0
- Gene
- pyruvate,P(i) dikinasee0
- Outcome
- activity of pyruvate,P(i) dikinasee0
- Direction
- fallse0
- Comparator
- illuminated plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“activity of pyruvate,P(i) dikinase in leaves of maize and Amaranthus palmeri rapidly falls on transferring illuminated plants to darkness”
Claim · model-written summary
Illumination rapidly increased enzyme activity after dark treatment, with final activity depending on light intensity.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- Illuminatione0
- Outcome
- activity of the enzymee0
- Direction
- increasee0
- Qualifier
- intensity of the incident lighte0
- Comparator
- dark-treated plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Illumination of dark-treated plants results in an immediate rapid increase in activity of the enzyme, the final activity reached being dependent on the intensity of the incident light”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Activation in dark-treated maize leaf extracts required a thiol and P(i).
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Activation of the enzyme in extracts of dark-treated maize leaves after gel filtration on Sephadex G-25 requires a thiol and P(i)”
Claim · model-written summary
Arsenate replaced P(i) for enzyme activation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The P(i) requirement for activation can be replaced by arsenate”
e1“dark-treated maize leaves”
Claim · model-written summary
AMP and GMP inhibited enzyme activation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Activation of the enzyme is inhibited by AMP and GMP”
e1“dark-treated maize leaves”
Claim · model-written summary
ADP and ATP possibly inhibited enzyme activation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“possibly also by ADP and ATP”
e1“Activation of the enzyme is inhibited by AMP and GMP and possibly also by ADP and ATP”
e2“dark-treated maize leaves”
Claim · model-written summary
Activation after G-200 filtration required a heat-labile component excluded by G-25.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Activation of the enzyme after gel filtration on Sephadex G-200 also requires a heat-labile component that is excluded by Sephadex G-25”
e1“dark-treated maize leaves”
Claim · model-written summary
ADP with a thiol inactivated the active enzyme, faster in air than without oxygen.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- ADP in the presence of a thiole0
- Outcome
- rate of inactivatione0
- Direction
- fastere0
- Qualifier
- in aire0
- Comparator
- oxygen-free atmospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“active enzyme isolated from illuminated leaves is inactivated by ADP in the presence of a thiol, the rate of inactivation being very much faster in air than in an oxygen-free atmosphere”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Reactivation of ADP-inactivated enzyme required a thiol, P(i), and a chromatographically distinct component.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Outcome
- Reactivation of the ADP-inactivated enzymee0
- Qualifier
- a thiol, P(i) and a component excluded by Sephadex G-25 but considerably retarded by Sephadex G-200e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reactivation of the ADP-inactivated enzyme requires a thiol, P(i) and a component excluded by Sephadex G-25 but considerably retarded by Sephadex G-200”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
The active enzyme was rapidly irreversibly inactivated without a thiol.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Outcome
- active enzymee0
- Qualifier
- absence of a thiole0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“active enzyme is rapidly and irreversibly inactivated in the absence of a thiol”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Sodium diethyldithiocarbamate and tetraethylthiuram disulphide accelerated enzyme inactivation.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- sodium diethyldithiocarbamate and tetraethylthiuram disulphidee0
- Outcome
- Inactivatione0
- Direction
- acceleratede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inactivation is accelerated by both sodium diethyldithiocarbamate and tetraethylthiuram disulphide”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Dithiothreitol completely reactivated enzyme inactivated by those reagents without P(i).
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- dithiothreitole0
- Outcome
- enzyme inactivated by these reagentse0
- Qualifier
- does not require P(i)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enzyme inactivated by these reagents is completely reactivated by incubation with dithiothreitol. This reactivation does not require P(i)”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Diethyldithiocarbamate stabilized inactive enzyme from dark-treated leaves.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- diethyldithiocarbamatee0
- Outcome
- inactive enzymee0
- Direction
- stabilizede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inactive enzyme from dark-treated leaves is stabilized by diethyldithiocarbamate”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Dithiothreitol alone partially activated inactive enzyme from dark-treated leaves.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie2
- Treatment
- dithiothreitol alonee0
- Outcome
- inactive enzymee1
- Direction
- partially activatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“can be partially activated by dithiothreitol alone”
e1“inactive enzyme from dark-treated leaves”
e2“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Complete reactivation required both dithiothreitol and P(i).
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Outcome
- complete reactivatione0
- Qualifier
- both dithiothreitol and P(i)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“complete reactivation requires both dithiothreitol and P(i)”
e1“leaves of maize and Amaranthus palmeri”
Claim · model-written summary
Three thiol reagent treatments markedly inhibited enzyme activity.
- Taxon
- maize and Amaranthus palmeriZea maysAmaranthus palmerie1
- Treatment
- p-chloromercuribenzoate, gamma-(p-arsenophenyl)-n-butyrate and an equimolar mixture of arsenite and 2,3-dimercaptopropan-1-ole0
- Outcome
- enzyme activitye0
- Direction
- inhibitede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enzyme activity is markedly inhibited by the thiol reagents p-chloromercuribenzoate, gamma-(p-arsenophenyl)-n-butyrate and an equimolar mixture of arsenite and 2,3-dimercaptopropan-1-ol”
e1“leaves of maize and Amaranthus palmeri”
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