Heterogeneous photochemical and chloroplasts mediated activation of spinach fructose-1,6-bisphosphatase
Maheshwari, V.; Bhardwaj, R.; Sharma, D.; Nagar, S.
Biochemical and Biophysical Research Communications 152(2): 668-673
1988
ISSN/ISBN: 0006-291X PMID: 3284525 Document Number: 306916
A heterogenous photochemical electron relay system was constructed, mimicking the chloroplasts 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 heterogenous photochemical system while chloroplasts mediated redox activation essentially required ferredoxin. The heterogenous 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.