scholarly journals Partial uncoupling, or inhibition of electron transport rate, have equivalent effects on the relationship between the rate of ATP synthesis and proton-motive force in submitochondrial particles

FEBS Letters ◽  
1985 ◽  
Vol 181 (2) ◽  
pp. 323-327 ◽  
Author(s):  
M.Catia Sorgato ◽  
Giovanna Lippe ◽  
Serena Seren ◽  
Stuart J. Ferguson
Keyword(s):  
Electron Transport ◽  
Electron Transport Rate ◽  
Atp Synthesis ◽  
Proton Motive Force ◽  
Motive Force ◽  
Transport Rate ◽  
Submitochondrial Particles ◽  
The Relationship

A Diterpene γ-Lactone Derivative from Pterodon polygalaeflorus Benth. as a Photosystem II Inhibitor and Uncoupler of Photosynthesis

2006 ◽  
Vol 61 (3-4) ◽  
pp. 227-233 ◽  
Author(s):  
Beatriz King-Díaz ◽  
Flávio J. L. dos Santos ◽  
Mayura M. M. Rubinger ◽  
Dorila Piló -Veloso ◽  
Blas Lotina-Hennsen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Transport Rate ◽  
Atp Synthesis ◽  
Transport Rate ◽  
Hill Reaction ◽  
Oxygen Evolving Complex ◽  
Photosynthesis Inhibition ◽  
Chlorophyll A Fluorescence Transient ◽  
Oxygen Evolving

6α,7β-Dihydroxyvouacapan-17β-oic acid (1) was isolated from Pterodon polygalaeflorus Benth. Modification of 1 yielded 6α-hydroxyvouacapan-7β,17β-lactone (2) and then 6-oxovouacapan- 7β,17β-lactone (3). Photosynthesis inhibition by 3 was evaluated in spinach chloroplasts. The uncoupled non-cyclic electron transport rate and ATP synthesis were inhibited by 3, which behaved as a Hill reaction inhibitor. Furthermore, 3 acted as an uncoupler because it enhanced the basal and phosphorylating electron transport rate on thylakoids. This last property of 3 was corroborated when it was observed that it enhances the Mg2+-ATPase activity. In contrast, 3 did not affect photosystem I (PSI) activity. Analysis of the partial photosystem II (PSII) reactions from water to DCPIPox and water to silicomolybdate allowed to locate the inhibition sites at the redox components of PSII. The OJIP test of the chlorophyll a fluorescence transient confirmed that the inhibition sites were 1.) the oxygen-evolving complex (OEC) and 2.) by the formation of silent centers in the non-QA reducing centers.

scholarly journals Investigating on relationship between effective quantum efficiency and irradiance

2017 ◽  
Author(s):  
Zi-Piao Ye ◽  
Shuang-Xi Zhou ◽  
Xiao-Long Yang ◽  
Hua-Jing Kang ◽  
Piotr Robakowski
Keyword(s):  
Excited State ◽  
Electron Transport ◽  
Quantum Efficiency ◽  
Cross Section ◽  
Electron Transport Rate ◽  
Photosynthetic Pigment ◽  
Transport Rate ◽  
Absorption Cross ◽  
Ps Ii ◽  
The Relationship

AbstractModels describing the relationship between effective quantum efficiency of PS II (ΦPSII) and irradiance (I) are routinely used to determine how irradiance influences effective quantum efficiency and photosynthetic electron transport rate (ETR). However, with no single model one can accurately describe the relationship between ΦPSII and I, and explain the interdependence between ΦPSII and biophysical properties of photosynthetic pigments, especially in plants growing under low level irradiances. Basing on the mechanistic model of photosynthetic electron transport rate we have developed the model of the relationship between ΦPSII and I. The new model reveals that ΦPSII increases with photochemistry (kP) and heat dissipation (kD). Furthermore, the values of key parameters calculated using the new model were compared with the values calculated with two other empirical models. The new model was perfectly fitted to the light-response curves of ΦPSII. The key calculated photosynthetic parameters: maximum ΦPSII, maximum ETR and their corresponding saturation irradiance were close to the measured values. In addition, our model associates ΦPSII with intrinsic features of photosynthetic pigments. We concluded that ΦPSII decreased with increasing I due to the decrease in the effective absorption cross-section of photosynthetic pigments molecules.HighlightA model of the relationship between effective quantum efficiency of PS II (ΦPSII) and irradiance (I) has been developed. Using this new model it was found that ΦPSII decreased with increasing I due to the decrease in the effective absorption cross-section of photosynthetic pigments molecules.AbbreviationsETRElectron transport rateETRmaxMaximum electron transport rateFSteady-state fluorescenceFm′Maximum fluorescence in the lightFvVariable fluorescence yield of the dark-adapted leafgiDegeneration of energy level of photosynthetic pigment molecules in the ground state igkDegeneration of energy level of photosynthetic pigment molecules in the excited state kIIrradianceNPQNon-photochemical quenchingN0Total light-harvesting pigment moleculesPARsatSaturation irradiance corresponding to ETRmaxkPRate of photochemical reactionkDRate of non-radiative heat dissipationPS IIPhotosystem IIaeInitial slope of light-response curve of electron transport rateα′Fraction of light absorbed by PS IIβ′Leaf absorptanceξ1Probability of photochemistryξ2Probability of non-radiative heat dissipationξ3Probability of fluorescenceσikEigen-absorption cross-section of photosynthetic pigment from ground state i to excited state k due to light illuminationEffective optical absorption cross-section of photosynthetic pigment molecule from ground state i to excited state k due to light illuminationφExciton-use efficiency in PS IIτAverage lifetime of the photosynthetic pigment molecules in the lowest excited stateΣPSIIEffective quantum efficiency of PS II

scholarly journals Updating the steady state model of C4 photosynthesis

2021 ◽  
Author(s):  
Susanne von Caemmerer
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Electron Transport Rate ◽  
Transport Rate ◽  
Initial Slope ◽  
Carboxylase Activity ◽  
Quantitative Correlation ◽  
Steady State Model ◽  
State Models

AbstractC4 plants play a key role in world agriculture. For example, C4 crops such as maize and sorghum are major contributors to both first and third world food production and the C4 grasses sugarcane; miscanthus and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C4 photosynthesis, steady state models of leaf photosynthesis provide and important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here the C4 photosynthetic model by von Caemmerer and Furbank (1999) has been updated with new kinetic parameterisation and temperature dependencies added. The parameterisation was derived from experiments on the C4 monocot, Setaria viridis, which for the first time provides a cohesive parametrisation. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro PEP carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow and equations have been added to calculate electron transport rate from measured CO2 assimilation rates.HighlightThe C4 photosynthesis model by von Caemmerer and Furbank (1999) has been updated. It now includes temperature dependencies and equations to calculate electron transport rate from measured CO2 assimilation rates.

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