Regulatory properties of Rana esculenta liver D-fructose-1,6-bisphosphate 1-phosphohydrolase and their comparison with properties of other vertebrate liver isoenzymes.
D-Fructose-1,6-bisphosphate 1-phosphohydrolase [EC 3.1.3.11] (Fru-1,6P2ase), a regulatory enzyme of gluconeogenesis, was isolated from Rana esculenta liver in homogeneous from with approximately 30% yield. Basic kinetic properties of the enzyme and its subunit molecular weight were determined. Km is 1.72 microM. Like other vertebrate Fru-1,6P2ase, the frog liver enzyme is inhibited by fructose-2,6-bisphosphate (Fru-2,6P2) competitively, Ki is 78 nM and by AMP allosterically, I0.5 is 10.9 microM. Both inhibitors (Fru-2,6P2 and AMP) act synergistically on liver Fru-1,6-P2ase. Ki for Fru-2,6P2 determined in the presence of 1-10 microM of AMP were 35-2 nM, respectively. Maximum activity was found at pH 7.5. Like other Fru-1,6P2ases, the frog enzyme requires magnesium ions for its activity and is activated by potassium ions; the Ka for Mg2+ is 267 microM, Ka for K+ is 77 mM. The subunit molecular weight of the frog liver Fru-1,6P2ase was 37,300 Da. A great similarity between regulatory properties of frog liver Fru-1,6P2ase and liver enzymes of other vertebrates, suggests a similar regulation of gluconeogenesis in amphibia and other vertebrates.
D000249:Adenosine Monophosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D005635:Fructosediphosphates / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D008970:Molecular Weight; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D011817:Rabbits; D011893:Rana esculenta / Q000378:metabolism*; D051381:Rats; D013045:Species Specificity; D013552:Swine; D014714:Vertebrates / Q000378:metabolism*