Fructose-1,6-bisphosphatase in stage VI frog oocytes: evidence for an active enzyme in vivo.
The characterization of fructose-1,6-bisphosphatase in stage VI oocytes from the frog Caudiverbera caudiverbera, as well as the in vivo activity, is reported. The enzyme has a subunit molecular weight of approximately 43,500, has an apparent Km value of 17 microM for fructose-1,6-bisP, and is inhibited by substrate concentrations beyond 100 microM. AMP and fructose-2,6-bisP are strong inhibitors of oocyte fructose-1,6-bisphosphatase activity with Ki values of 9 and 2 microM respectively. Inhibition by AMP is cooperative with a nH value of 2.2. In vivo fructose-1,6-bisphosphatase activity was demonstrated by microinjection of [U-14C]- or [6-32P]fructose-1,6-bisP and subsequent chromatographic separation and identification of labeled products. The relevance of these findings for the metabolism of glucose in frog oocytes is discussed.
Preller
A
A
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
Guixé
V
V
Kessi
E
E
Ureta
T
T
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001001:Anura / Q000502:physiology*; D006597:Fructose-Bisphosphatase / Q000187:drug effects / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009865:Oocytes / Q000201:enzymology* / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology
D000249:Adenosine Monophosphate; D006597:Fructose-Bisphosphatase