Stimulation of photophosphorylation by ascorbate as a function of light intensity

When isolated, stroma-free thylakoids are illuminated in the presence of ADP and orthophosphate in the absence of any electron acceptor except O2, the addition of ascorbate stimulates electron transport through the formation of the radical monodehydroascorbate and the coupled synthesis of ATP (G. Fo...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1996-12, Vol.112 (4), p.1509-1511
Main Authors: Forti, G. (Universita di Milano, Italy.), Elli, G
Format: Article
Language:English
Subjects:
ACIDE ASCORBIQUE
ACIDO ASCORBICO
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
Adenosine triphosphatases
ADENOSINE TRIPHOSPHATE
adenosinetriphosphatase
ADENOSINTRIFOSFATO
ascorbate peroxidase
ascorbic acid
ATPASA
ATPASE
Bioenergetics
Biological and medical sciences
BIOSINTESIS
BIOSYNTHESE
biosynthesis
Chlorophylls
Chloroplasts
dehydroascorbic acid
electron transfer
enzyme activity
Enzymes
FEUILLE
FOSFORILACION
FOTOSINTESIS
FOTOSISTEMAS
free radicals
Fundamental and applied biological sciences. Psychology
HOJAS
leaves
light intensity
LUMIERE
Luminous intensity
LUZ
Metabolism
Metabolism. Physicochemical requirements
OXIDORREDUCTASAS
OXIRREDUCION
OXYDOREDUCTASE
OXYDOREDUCTION
PHOSPHORYLATION
Photophosphorylation
PHOTOSYNTHESE
photosystem I
PHOTOSYSTEME
Plant physiology and development
Plants
Protons
Spinach
SPINACIA OLERACEA
THYLAKOIDE
Thylakoids
TILACOIDES
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Summary:When isolated, stroma-free thylakoids are illuminated in the presence of ADP and orthophosphate in the absence of any electron acceptor except O2, the addition of ascorbate stimulates electron transport through the formation of the radical monodehydroascorbate and the coupled synthesis of ATP (G. Forti and G. Elli [1995] Plant Physiol 109: 1207-1211). The stimulation is shown here to be higher at low light intensity. These observations are explained in terms of the increase of the electron transport rate by ascorbate which established a higher value of the steady-state pH gradient, causing activation of ATP synthase, which is known to be dependent on the level of the H+-electrochemical potential difference, and a higher rate of proton flux across the membranes available for utilization by ATP synthesis
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.112.4.1509