Spinach (Spinacia oleracea) chloroplast sedoheptulose-1,7-bisphosphatase. Activation and deactivation, and immunological relationship to fructose-1,6-bisphosphatase.
In this paper we study activation by dithiothreitol and reduced thioredoxins and deactivation by oxidized thioredoxins f of sedoheptulose-1,7-bisphosphatase. The behaviour of the enzyme when chromatographed on a thioredoxin-Sepharose column is also described. The enzyme is autoxidizable upon removal of reducing agents, and is activated when reduced by any of the thioredoxins. This mechanism may allow the regulation of the Calvin cycle upon light-dark and dark-light transitions. The formation of a stable complex between enzyme and thioredoxin could explain the inhibitory effect of high thioredoxin concentrations. The use of immunological techniques shows that sedoheptulose-1,7-bisphosphatase and fructose-1,6-bisphosphatase are poorly related immunologically.
Cadet
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Centre de Biotechnologie Agro-Industrielle, Institut National Agronomique Paris-Grignon, Thiverval-Grignon, France.
Meunier
J C
JC
D000596:Amino Acids / Q000032:analysis; D002736:Chloroplasts / Q000201:enzymology*; D002846:Chromatography, Affinity; D004789:Enzyme Activation / Q000187:drug effects; D006597:Fructose-Bisphosphatase / Q000276:immunology; D005779:Immunodiffusion; D007700:Kinetics; D010744:Phosphoric Monoester Hydrolases / Q000276:immunology / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D013879:Thioredoxins / Q000494:pharmacology
D000596:Amino Acids; D013879:Thioredoxins; D006597:Fructose-Bisphosphatase; D010744:Phosphoric Monoester Hydrolases; C022627:sedoheptulose-bisphosphatase