Regulation of rat-kidney cortex fructose-1,6-bisphosphatase activity. I. Effects of fructose-2,6-bisphosphate and divalent cations.
1. The native rat-kidney cortex Fructose-1,6-BPase is differentially regulated by Mg2+ and Mn2+. 2. Mg2+ binding to the enzyme is hyperbolic and large concentrations of the cation are non-inhibitory. 3. Mn2+ produces a 10-fold rise in Vmax higher than Mg2+. [Mn2+]0.5 is much larger than [Mg2+]0.5. At elevated [Mn2+] inhibition is observed. 4. Mg2+ and Mn2+ produce antagonistic effects on the inhibition of the enzyme by high substrate. 5. Fru-2,6-P2 inhibits the enzyme by rising the S0.5 and favouring a sigmoidal kinetics. 6. The inhibition by Fru-2,6-P2 is released by Mg2+ and more powerfully by Mn2+ increasing the I0.5.
Sola
M M
MM
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Granada, Spain.
Oliver
F J
FJ
Salto
R
R
Gutiérrez
M
M
Vargas
A M
AM
D000818:Animals; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors / Q000187:drug effects*; D005635:Fructosediphosphates / Q000494:pharmacology*; D007672:Kidney Cortex / Q000187:drug effects* / Q000201:enzymology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D005635:Fructosediphosphates; D008345:Manganese; C027652:fructose 2,6-diphosphate; D006597:Fructose-Bisphosphatase; D008274:Magnesium