beta-D-fructose 1,6-bisphosphate + H2O = beta-D-fructose 6-phosphate + phosphate Activated by phosphoenolpyruvate (PEP) and by high concentrations of monovalent cations, NH(4)(+) being most effective. Is inhibited by two types of compounds which apparently act on the enzyme at different sites. The first group consists of nucleoside monophosphates (most effective are AMP and dAMP), phosphorylated coenzymes, and denatured DNA and RNA, whose inhibition is competed by PEP. The second group, whose inhibition is not competed by PEP, consists of highly phosphorylated nucleotides (pppGpp and pppApp are most effective), nucleoside di- and triphosphates, and PPi. Optimum pH is 8. Carbohydrate biosynthesis; gluconeogenesis. Constitutively expressed. Expressed at a fairly constant level in cells undergoing glycolysis or gluconeogenesis. Disruption of fbp alone (or ywjI alone) does not affect growth on various carbon sources. But the ywjI fbp double mutant is unable to grow with carbon sources demanding FBPase activity, i.e. glycerol, malate, and a mixture of succinate and glutamate. Belongs to the FBPase class 3 family. Extended N-terminus.