1987
DOI: 10.1071/pp9870451
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Inorganic Phosphate Concentration in the Stroma of Isolated Chloroplasts and Its Influence on Photosynthesis

Abstract: The concentration of inorganic orthophosphate (Pi) was determined in the stroma of isolated chloroplasts during photosynthesis under Pi-saturated and Pi-limited conditions. Pi was determined calorimetrically or by high performance liquid chromatography of extracts of chloroplasts labelled with 32Pi. When chloroplasts were illuminated in the absence of added Pi, photosynthesis soon declined due to Pi-depletion. After 5 min in the light, photosynthesis had declined to 2% of the maximum rate. At this point, strom… Show more

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Cited by 29 publications
(22 citation statements)
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“…Although the metabolic signal responsible for regulation of the ATP synthase is not yet known, a well-established model involves modulation by changes in stromal P i concentrations (Robinson and Giersch 1987;Sharkey 1990;Takizawa et al 2007). If this model is relevant to C 4 plant chloroplasts, then changes in chloroplast P i levels would control ATP synthase conductance in response to changes Fig.…”
Section: Discussionmentioning
confidence: 99%
“…Although the metabolic signal responsible for regulation of the ATP synthase is not yet known, a well-established model involves modulation by changes in stromal P i concentrations (Robinson and Giersch 1987;Sharkey 1990;Takizawa et al 2007). If this model is relevant to C 4 plant chloroplasts, then changes in chloroplast P i levels would control ATP synthase conductance in response to changes Fig.…”
Section: Discussionmentioning
confidence: 99%
“…For this reason, we have determined the bulk of phosphate esters in nonaqueously isolated chloroplasts. Knowing that inorganic phosphate concentrations are very low at high rates of photosynthesis in the presence of high CO2 concentrations (Walker and Sivak 1986;Robinson and Giersch 1987) and that total phosphate contents (organic plus inorganic phosphate) can be considered constant within the time scale of our experiments owing to the obligatory countertransport of phosphate and phosphate esters which is catalyzed by the phosphate translocator of the chloroplast envelope, we have assumed the total phosphate concentration in our sunflower chloroplasts to be 30 mM (see Dietz and Heber 1989). Subtraction of measured organic phosphates from this yields concentrations of inorganic phosphate.…”
Section: Still It Is Obvious Frommentioning
confidence: 99%
“…(i) The K m value in thylakoids, at least in the case of P i , may be the same, if not much lower, than the one obtained in the E. coli system, as in the case of the thylakoid ATP/ADP carrier (6). (ii) To accurately determine the P i concentration in organelles such as chloroplast (stroma) seems to be difficult; thus, values ranging between Յ1 and ϳ10 mM have been reported (27)(28)(29). (iii) When it comes to Na ϩ , its physiological concentration in the stroma is ϳ100 mM (30).…”
Section: Eantr1 Controlmentioning
confidence: 99%