Photosynthesis by isolated chloroplasts. Reversal of orthophosphate inhibition by Calvin-cycle intermediates.
1. The orthophosphate inhibition of photosynthesis by isolated spinach chloroplasts can be reversed by 3-phosphoglycerate, dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, fructose 6-phosphate and fructose 1,6-diphosphate. 2. Metabolically related compounds such as ribulose 1,5-diphosphate, glucose 6-phosphate, 6-phosphogluconate and phosphoenolpyruvate are ineffective. 3. The kinetics of reversal are characteristic of the intermediate used, but, in each instance, the onset of oxygen evolution is accompanied by a carbon dioxide fixation and except with 3-phosphoglycerate the stoicheiometry is close to unity. 4. The nature of orthophosphate inhibition and its reversal is discussed in relation to metabolic control of photosynthesis.
D002245:Carbon Dioxide / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D003864:Depression, Chemical; D005985:Glyceraldehyde / Q000378:metabolism; D005988:Glyceric Acids / Q000378:metabolism*; D005994:Glycerophosphates / Q000378:metabolism*; D006600:Hexosephosphates / Q000378:metabolism*; D007700:Kinetics; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D010710:Phosphates / Q000494:pharmacology*; D010788:Photosynthesis; D011048:Polarography
D005988:Glyceric Acids; D005994:Glycerophosphates; D006600:Hexosephosphates; D010710:Phosphates; D002245:Carbon Dioxide; D005985:Glyceraldehyde; D010100:Oxygen