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.
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
A
A
Preller
V
V
Guixé
E
E
Kessi
T
T
Ureta
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