Heterogeneous photochemical and chloroplasts mediated activation of spinach fructose-1,6-bisphosphatase.
A heterogeneous photochemical electron relay system was constructed, mimicking the chloroplast electron transport reaction, in order to activate fructose-1,6-bisphosphatase in light. The photocatalyst acridine orange or proflavin sensitizes EDTA dependent reduction of ferredoxin. In a complete system, consisting of a dye-donor couple, ferredoxin, thioredoxin and ferredoxin-thioredoxin reductase, light activation of purified spinach fructose-1,6-bisphosphatase was observed in vitro. The ferredoxin was not essential for activation of fructose-1,6-bisphosphatase using heterogeneous photochemical system while chloroplasts mediated redox activation essentially required ferredoxin. The heterogeneous photochemical system activated fructose-1,6-bisphosphatase by about 6 fold similar to chloroplasts mediated ferredoxin dependent redox activation. These observations suggest that a thiol mediator is essential for the reductive activation of carboxylating enzymes of photosynthesis. The mechanism of activation is discussed.
Maheshwari
V
V
School of Biochemistry, University of Indore, India.
Bhardwaj
R
R
Sharma
D
D
Nagar
S
S
D000165:Acridine Orange; D002384:Catalysis; D002736:Chloroplasts / Q000201:enzymology*; D004579:Electron Transport; D004789:Enzyme Activation; D010084:Oxidation-Reduction; D010447:Peptide Hydrolases / Q000378:metabolism*; D010788:Photosynthesis; D011370:Proflavine; D013879:Thioredoxins / Q000378:metabolism
D013879:Thioredoxins; D011370:Proflavine; D010447:Peptide Hydrolases; C020152:fructose 1,6-bisphosphatase converting enzyme; D000165:Acridine Orange