Effect of substrate and AMP on the reversal of Zn2+ inhibition of turkey liver fructose-1,6-bidphosphatase by chelators

Influence of dietary zinc deficiency and parenteral zinc on rat liver fructose 1,6-bisphosphatase activity

Fructose 1,6-bisphosphatase activity in liver of rats fed a zinc deficient diet was decreased to 60% of that in zinc adequate controls. Activity in the zinc deprived rats was not restored to control values by in vitro addition of EDTA. When a physiological dose of zinc was tube fed to the depleted rats, activity increased approximately 150% within 0.5 hr of the dose, and by 1 hr plateaued to a level seen in zinc adequate controls. A significant transient decrease in activity occurred following an intraperitoneal zinc load. This is reversible by in vitro addition of EDTA. These results suggest that rat liver fructose 1,6-bisphosphatase activity is highly sensitive to zinc in vivo as has been demonstrated in vitro.

Immobilization of chicken liver fructose 1,6-bisphosphatase on CNBr-activated Sepharose

Chicken liver fructose 1,6-bisphosphatase is readily immobilized on CNBr-activated Sepharose. The immobilization alters some enzymatic properties. They include broader pH activity curve, loss of activation by K+ or NH+4, increased resistance to inactivation by trypsin, decreased sensitivity to AMP inhibition, and loss of cooperative interaction among AMP-binding sites. The immobilized enzyme retains about 38% or 19% of the specific activity of the native enzyme when the activity is measured in the absence or presence of K+, respectively.