The reactive cysteine residue of pig kidney fructose 1,6-bisphosphatase is related to a fructose 2,6-bisphosphate allosteric site.
Modification of a highly reactive cysteine residue of pig kidney fructose 1,6-bisphosphatase with N-ethylmaleimide results in the loss of activation of the enzyme by monovalent cations. Low concentrations of fructose 2,6-bisphosphate or high (inhibitory) levels of fructose 1,6-bisphosphate protect the enzyme against the loss of monovalent cation activation, while non-inhibitory concentrations of the substrate gave partial protection. The allosteric inhibitor AMP markedly increases the reactivity of the cysteine residue. The results indicate that fructose 2,6-bisphosphate can protect the enzyme against the loss of potassium activation by binding to an allosteric site. High levels of fructose 1,6-bisphosphate probably inhibit the enzyme by binding to this allosteric site.
Reyes
A
A
Hubert
E
E
Slebe
J C
JC
D000818:Animals; D001665:Binding Sites; D003545:Cysteine / Q000032:analysis*; D004789:Enzyme Activation; D005033:Ethylmaleimide / Q000494:pharmacology; D006597:Fructose-Bisphosphatase / Q000032:analysis*; D005635:Fructosediphosphates / Q000378:metabolism*; D006598:Hexosediphosphates / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D011188:Potassium / Q000494:pharmacology; D013552:Swine
D005635:Fructosediphosphates; D006598:Hexosediphosphates; C027652:fructose 2,6-diphosphate; D006597:Fructose-Bisphosphatase; D003545:Cysteine; C029063:fructose-1,6-diphosphate; D005033:Ethylmaleimide; D011188:Potassium