Modulation of Chloroplast Fructose-1,6-bisphosphatase Activity by Light

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Abstract
Inhibitor experiments indicate that light effect mediatorII which is reductively activated by transfer of electrons from the photosynthetic electron transport system at or beyond ferredoxin, is involved in activation by light of fructose-1,6-bisphosphatase [EC 3.1.3.11] in the pea [Pisum sativum cv. Little Marvel] plant. Activation proceeds optimally when the pH is low and Mg2+ is 10 mM. Modulation by light results in increases in maximal velocity, apparently as a result of changes in enzyme conformation. Pea leaf thylakoids are effective in modulating the activity of glyceraldehyde-3-phosphate dehydrogenase but not of fructose-1,6-bisphosphatase or G-6-P dehydrogenase in Kalanchoe [cv. Tetra Vulcan] stromal extracts. There is apparently species specificity for modulation of some, but not all, of the modulatable enzymes.