Regulation of fructose, 1,6-bisphosphatase by histidine under gluconeogenic conditions

Fructose 1,6-bisphosphatase (EC 3.1.3.11) requires a free divalent metal and a metal chelate for optimum activity in the neutral pH range. The latter requirement can be satisfied by histidine, which appears to function as the chelating metabolite in vivo. Under fasting conditions, the concentrations of histidine in rabbit liver vary in the range required for activation of fructose bisphosphatase, and the enzyme itself is modified so that it becomes more responsive to histidine.