Year: 1975
Type: article
Abstract: The Emerson enhancement effect was evaluated in the intact spinach (Spinacia oleracea var. Long Standing Bloomsdale) chloroplast by monitoring the uptake of (14)CO(2) during illumination by 640 nm and 720 nm lights. Low levels (about 10 mum) of fructose 1,6-diphosphate, ribose 5-phosphate, and glycerate 3-phosphate stimulated the rate of photosynthesis and abolished enhancement values observed in their absence. Concentrations of the two sugar phosphates at levels of 1 mm responded similarly. In contrast, 1 mm glycerate 3-phosphate inhibited the rate of photosynthesis and increased enhancement. The exchange of glycerate 3-phosphate for glyceraldehyde 3-phosphate was speculated to be a factor underlying the decrease in photosynthesis and the increase in enhancement. Glucose 6-phosphate, NADPH, and l-malate did not influence photosynthesis or enhancement.The uncoupler, p-trifluoromethoxyphenylhydrazone, decreased the rate of photosynthesis but did not change the enhancement values. ATP (0.2 to 1 mm) had an occasional stimulating effect on CO(2) fixation but no effect on enhancement. Magnesium ions inhibited photosynthesis and decreased the enhancement values. It was concluded that the enhancement phenomenon reflects events of the photosynthetic carbon reduction cycle as well as the photochemical act.
Source: PLANT PHYSIOLOGY
DOI: 10.1104/pp.55.5.799
Authors: Dwight G. Peavey, Martin Gibbs
Institution: Brandeis University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2064316913