Purification and properties of Oxidized and reduced forms of Hepatic fructose 1,6-bisphosphatase.
D-Fructose 1,6-bisphosphate 1-phosphohydrolase (EC 3.1.3.11) was isolated from rat liver in two forms: "A," isolated in the presence, and "B," isolated in the absence of dithiothreitol. Both forms had an apparently identical molecular weight of approximately 37,000/subunit and the same Km for fructose 1,6-bisphosphate of 2 microM. However, the Ki of the AMP inhibition of form A was 140 microM and of form B, 370 microM. With form B the same inhibition as with form A was reached by incubating the enzyme with dithiothreitol. The two forms of the enzyme differed in their total, as well as in their number of fast reacting thiol groups. Form A was the more reduced form, exhibiting 22.4 thiol groups/molecule, 2.5 of them fast reacting with 5,5'-dithiobis-(2-nitrobenzoic acid). Only 0.5 fast reacting groups and a total of 19.2 were found with form B. The fast reacting thiol groups disappeared when assayed in the presence of AMP. It is suggested that a redox reaction alters a site that influences the inhibitory action of AMP, so as to regulate the activity of fructose 1,6-bisphosphatase.
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D006597:Fructose-Bisphosphatase / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D051381:Rats
D000249:Adenosine Monophosphate; D006597:Fructose-Bisphosphatase; D004229:Dithiothreitol