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Effect Of Glyoxylate On The Sensitivity Of Net Photosynthesis To Oxygen (The Warburg Effect) In Tobacco, David J. Oliver
Effect Of Glyoxylate On The Sensitivity Of Net Photosynthesis To Oxygen (The Warburg Effect) In Tobacco, David J. Oliver
David J. Oliver
The addition of glyoxylate to tobacco (Nicotiana tabacum) leaf discs inhibited glycolate synthesis and photorespiration and increased net photosynthetic 14CO2 fixation. This inhibition of photorespiration was investigated further by studying the effect of glyoxylate on the stimulation of photosynthesis that occurs when the atmospheric O2 level was decreased from 21 to 3% (the Warburg effect). The Warburg effect is usually ascribed to the increased glycolate synthesis and metabolism that occurs at higher O2 concentrations. Photosynthesis in control discs increased from 59.1 to 94.7 micromoles of CO2 per gram fresh weight per hour (a 60% increase) when the O2 level was …
Inhibition Of Photorespiration And Increase Of Net Photosynthesis In Isolated Maize Bundle Sheath Cells Treated With Glutamate Or Aspartate, David J. Oliver
Inhibition Of Photorespiration And Increase Of Net Photosynthesis In Isolated Maize Bundle Sheath Cells Treated With Glutamate Or Aspartate, David J. Oliver
David J. Oliver
Net photosynthetic 14CO2 fixation by isolated maize (Zea mays) bundle sheath strands was stimulated 20 to 35% by the inclusion of L-glutamate or L-aspartate in the reaction mixture. Maximal stimulation occurred at a 7.5 mM concentration of either amino acid. Since the photosynthetic rate and the glutamate-dependent stimulation in the rate were equally sensitive to a photosynthetic electron transport inhibitor, 3-(p-chlorophenyl)-1,1-dimethylurea, it was concluded that glutamate did not stimulate CO2 fixation by supplying needed NADPH (NADH) through glutamate dehydrogenase. Treatment of the bundle sheath strands with glutamate inhibited glycolate synthesis by 59%. Photorespiration in this tissue, measured as the O2 …