Effects of irradiance and methyl viologen treatment on ATP, ADP, and activation of ribulose bisphosphate carboxylase in spinach leaves

Since activation of ribulose bisphosphate carboxylase (rubisco) by rubisco activase is sensitive to ATP and ADP in vitro, we aimed to test the correlation between ATP level and rubisco activation state in intact leaves of Spinacia oleracea L. in response to changes in irradiance and after feeding th...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1988-11, Vol.88 (3), p.850-853
Main Authors: Brooks, A, Portis, A.R. Jr, Sharkey, T.D
Format: Article
Language:English
Subjects:
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ADENOSINDIFOSFATO
ADENOSINE DIPHOSPHATE
ADENOSINE TRIPHOSPHATE
ADENOSINTRIFOSFATO
Biological and medical sciences
Carbon dioxide
Catalysis
Chloroplasts
Enzymes
ENZYMIC ACTIVITY
FEUILLE
Fundamental and applied biological sciences. Psychology
HOJAS
Irradiance
LEAVES
LIASAS
LYASE
LYASES
Metabolism
Photosynthesis
Physiological regulation
Plant physiology and development
Plants
RADIACIONES
RADIATION
RADIATIONS
RESPIRACION
RESPIRATION
Spinacea oleracea
Spinach
SPINACIA OLERACEA
Viologens
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Summary:Since activation of ribulose bisphosphate carboxylase (rubisco) by rubisco activase is sensitive to ATP and ADP in vitro, we aimed to test the correlation between ATP level and rubisco activation state in intact leaves of Spinacia oleracea L. in response to changes in irradiance and after feeding the electron acceptor methyl viologen. Leaves were exposed to various irradiances for 45 minutes at atmospheric partial pressures of CO2 and O2. After measuring the rate of CO2 assimilation, leaves were freeze-clamped in situ and the punched discs assayed for rubisco activity, and amounts of ribulose bisphosphate (RuBP), ATP, and ADP. The photosynthetic rate and the activation state of rubisco increased with increasing irradiance but the levels of RuBP, ATP, and ADP were not greatly affected. Methyl viologen fed leaves under low irradiance had rubisco activation states of 93% compared to 51% in control leaves. The ATP content of the leaves was also significantly higher and the ratio of ATP to ADP was 4.1 in methyl viologen fed leaves compared to 2.2 in control leaves. From these results and other published results we conclude that a correlation between ATP level and rubisco activation can be observed in intact leaves, but that during changes in irradiance some additional factors are involved in regulating rubisco activation.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.88.3.850