scholarly journals Action of calcium ions on spinach (Spinacia oleracea) chloroplast fructose bisphosphatase and other enzymes of the Calvin cycle

1980 ◽  
Vol 188 (3) ◽  
pp. 775-779 ◽  
Author(s):  
S A Charles ◽  
B Halliwell
Keyword(s):  
Calcium Ions ◽  
Spinacia Oleracea ◽  
Calvin Cycle ◽  
Complete Inhibition ◽  
Fructose Bisphosphatase ◽  
Spinach Chloroplasts ◽  
Fructose 1,6 Bisphosphate ◽  
Sedoheptulose Bisphosphatase

Thiol-treated spinach (Spinacia oleracea) chloroplast fructose bisphosphatase is powerfully inhibited by Ca2+ non-competitively with respect to its substrate, fructose 1,6-bisphosphate. 500 microM-Ca2+ causes virtually complete inhibition and the Ki is 40 microM. Severe inhibition of sedoheptulose bisphosphatase is also caused by Ca2+. A role for Ca2+ in regulation of the Calvin cycle in spinach chloroplasts is proposed.

scholarly journals Glutathione and ascorbic acid in spinach (Spinacia oleracea) chloroplasts. The effect of hydrogen peroxide and of Paraquat

1983 ◽  
Vol 210 (3) ◽  
pp. 899-903 ◽  
Author(s):  
M Y Law ◽  
S A Charles ◽  
B Halliwell
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Spinacia Oleracea ◽  
Reduced Glutathione ◽  
Oxidized Glutathione ◽  
Fructose Bisphosphatase ◽  
Physiological Conditions ◽  
Spinach Chloroplasts ◽  
Apparent Loss

The stroma of spinach chloroplasts contains ascorbic acid and glutathione at millimolar concentrations. [Reduced glutathione]/[oxidized glutathione] and [ascorbate]/[dehydroascorbate] ratios are high under both light and dark conditions and no evidence for a role of oxidized glutathione or dehydroascorbate in the dark-deactivation of fructose bisphosphatase could be obtained. Addition of H2O2 to chloroplasts in the dark decreases the above ratios, an effect that is reversed on illumination. Addition of Paraquat to illuminated chloroplasts caused a rapid oxidation of reduced glutathione and ascorbate, and apparent loss of dehydroascorbate. Paraquat rapidly inactivated fructose bisphosphatase activity, as assayed under physiological conditions.

Effects of Photoinhibition on Photosynthetic Carbon Metabolism in Intact Isolated Spinach Chloroplasts.

1987 ◽  
Vol 14 (4) ◽  
pp. 439 ◽  
Author(s):  
C Giersch ◽  
SP Robinson
Keyword(s):  
Carbon Flux ◽  
Co2 Fixation ◽  
Calvin Cycle ◽  
Chloroplast Envelope ◽  
Low Light ◽  
Spinach Chloroplasts ◽  
Fructose 1,6 Bisphosphatase ◽  
Photosynthetic Carbon Metabolism ◽  
Chloroplast Stroma ◽  
Fructose 1,6 Bisphosphate

Pools of intermediates of the Calvin cycle were measured during photosynthetic 14CO2 fixation by intact isolated spinach chloroplasts. Photoinhibitibn (illumination for 8 min with 4000 �mol m-2 s-1 light in the absence of bicarbonate) decreased the subsequently measured rate of CO2 fixation. Individual compounds were differently affected: the ribulose-1,5-bisphosphate (RuBP) pool was drastically lowered, while that of fructose-1,6-bisphosphate (FBP) was increased, suggesting that photoinhibition causes a limitation in RuBP regeneration. An increase in FBP and decrease in RuBP were not observed during photosynthesis in low light at rates of CO2 fixation comparable to those in photoinhibited chloroplasts. This indicates that changes of the metabolite pools induced by photoinhibition were not due solely to decreased rates of electron transport. Activities of RuBP carboxylase and fructose-1,6-bisphosphatase (FBPase) were decreased by the photoinhibitory treatment. However, the activity of both enzymes in photoinhibited chloroplasts was still well in excess of that required to sustain the measured rates of carbon flux. Photoinhibition largely abolished the light-induced proton gradient across the chloroplast envelope. The concomitant acidification of the chloroplast stroma could inhibit FBPase activity. It is concluded that photoinhibition does not result in irreversible modification of the FBPase protein but that its activity may be decreased by changes in pH and possibly other factors in the chloroplast stroma.

Microsequecing and cDNA cloning of the Calvin cycle/OPPP enzyme ribose-5-phosphate isomerase (EC 5.3.1.6) from spinach chloroplasts

1996 ◽  
Vol 30 (4) ◽  
pp. 795-805 ◽  
Author(s):  
William Martin ◽  
Katrin Henze ◽  
Josef Kellermann ◽  
Anke Flechner ◽  
Claus Schnarrenberger
Keyword(s):  
Cdna Cloning ◽  
Calvin Cycle ◽  
Spinach Chloroplasts

Thiocarbamate Inhibition of Fatty Acid Biosynthesis in Isolated Spinach Chloroplasts

Weed Science ◽  
1975 ◽  
Vol 23 (2) ◽  
pp. 100-104 ◽  
Author(s):  
R. E. Wilkinson ◽  
A. E. Smith
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Spinacia Oleracea ◽  
Lipid Synthesis ◽  
Metabolic Effects ◽  
Acid Biosynthesis ◽  
Spinach Chloroplasts ◽  
Physiological Range

EPTC (S-ethyl dipropylthiocarbamate) (33μM) and diallate [S-(2,3-dichloroallyl)diisopropylthiocarbamate] (90μM) inhibited the incorporation of 6 mM acetate-2-14C (Ac∗) by 80% and 65%, respectively, and the incorporation of 0.5μM malonate-2-14C (Mal∗) by 32% and 26%, respectively, into the lipids of spinach (Spinacia oleraceaL.) chloroplasts. The inhibition of Ac∗or Mal∗incorporation into lipids was not observed in the presence of excess Ac∗or Mal∗, respectively. Incorporation of palmitate-1-14C and oleate-1-14C into chloroplast lipids was inhibited by EPTC and diallate. Mal∗incorporation into dienoic fatty acids was inhibited by EPTC and diallate. The concentration of EPTC and diallate inhibiting lipid synthesis falls into the physiological range of these herbicides, explains some metabolic effects of these compounds, and fits as the mode of activity of these herbicides.

scholarly journals On the Activation of Fructose-1,6-bisphosphatase of Spinach Chloroplasts and the Regulation of the Calvin Cycle

1981 ◽  
Vol 113 (3) ◽  
pp. 507-511 ◽  
Author(s):  
Jacques PRADEL ◽  
Jean-Michel SOULIE ◽  
Jean BUC ◽  
Jean-Claude MEUNIER ◽  
Jacques RICARD
Keyword(s):  
Calvin Cycle ◽  
Spinach Chloroplasts ◽  
Fructose 1,6 Bisphosphatase

scholarly journals Spinach (Spinacia oleracea) chloroplast sedoheptulose-1,7-bisphosphatase. Activation and deactivation, and immunological relationship to fructose-1,6-bisphosphatase

1988 ◽  
Vol 253 (1) ◽  
pp. 243-248 ◽  
Author(s):  
F Cadet ◽  
J C Meunier
Keyword(s):  
Spinacia Oleracea ◽  
Calvin Cycle ◽  
Inhibitory Effect ◽  
Reducing Agents ◽  
Stable Complex ◽  
Dark Light ◽  
Sepharose Column ◽  
Fructose 1,6 Bisphosphatase ◽  
Immunological Relationship

In this paper we study activation by dithiothreitol and reduced thioredoxins and deactivation by oxidized thioredoxins f of sedoheptulose-1,7-bisphosphatase. The behaviour of the enzyme when chromatographed on a thioredoxin-Sepharose column is also described. The enzyme is autoxidizable upon removal of reducing agents, and is activated when reduced by any of the thioredoxins. This mechanism may allow the regulation of the Calvin cycle upon light-dark and dark-light transitions. The formation of a stable complex between enzyme and thioredoxin could explain the inhibitory effect of high thioredoxin concentrations. The use of immunological techniques shows that sedoheptulose-1,7-bisphosphatase and fructose-1,6-bisphosphatase are poorly related immunologically.

scholarly journals Properties of freshly purified and thiol-treated spinach chloroplast fructose bisphosphatase

1980 ◽  
Vol 185 (3) ◽  
pp. 689-693 ◽  
Author(s):  
S A Charles ◽  
B Halliwell
Keyword(s):  
Inorganic Phosphate ◽  
Physiological Significance ◽  
Fructose Bisphosphatase ◽  
Spinach Chloroplast ◽  
Significant Rate ◽  
Chloroplast Stroma ◽  
Fructose 1,6 Bisphosphate

Freshly purified spinach chloroplast fructose bisphosphatase is powerfully inhibited by inorganic phosphate competitively with respect to its substrate fructose 1,6-bisphosphate. The concentrations of phosphate and substrate in the chloroplast stroma are such that the enzyme in this form could not operate at a significant rate in vivo. Incubation of the enzyme with dithiothreitol for 24 h decreases the Km for fructose 1,6-bisphosphate from 0.8 to 0.033 mM, decreases the Km for Mg2+ from 9 to 2 mM and substantially alleviates inhibition by inorganic phosphate. The physiological significance of thiol activation of the enzyme is discussed.

scholarly journals Isolation and purification of chloroplastic spinach (Spinacia oleracea) sedoheptulose-1,7-bisphosphatase

1987 ◽  
Vol 241 (1) ◽  
pp. 71-74 ◽  
Author(s):  
F Cadet ◽  
J C Meunier ◽  
N Ferté
Keyword(s):  
Affinity Chromatography ◽  
Spinacia Oleracea ◽  
Higher Plant ◽  
Isolation And Purification ◽  
Fructose 1,6 Bisphosphate ◽  
Molecular Sieving

Higher-plant sedoheptulose-1,7-bisphosphatase was isolated and purified over 200-fold from spinach (Spinacia oleracea) chloroplast stromal extracts to apparent electrophoretic homogeneity by DEAE-Fractogel, molecular sieving on Sephadex G-200 and Blue B dye-matrix affinity chromatography. It is a protein of Mr 66,000, made up of two apparently identical subunits (Mr 35,000). The enzyme is activated by reduced thioredoxin fb in the presence of dithiothreitol. Its specificity towards sedoheptulose 1,7-bisphosphate versus fructose 1,6-bisphosphate is high, but not absolute.

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