Phosphofructokinase (EC 2.7.1.11) catalyses the reverse conversion of fructose 6-phosphate to fructose-1,6-bisphosphate, but this is not just the reverse reaction, because the co-substrates are different (and so thermodynamic requirements are not violated). The two enzymes each catalyse the conversion in one direction only, and are regulated by metabolites such as fructose 2,6-bisphosphate so that high activity of one of them is accompanied by low activity of the other. More specifically, fructose 2,6-bisphosphate allosterically inhibits fructose 1,6-bisphosphatase, but activates phosphofructokinase-I. Fructose 1,6-bisphosphatase is involved in many different metabolic pathways and found in most organisms. FBPase requires metal ions for catalysis (Mg2+ and Mn2+ being preferred) and the enzyme is potently inhibited by Li+.
^Marcus F, Harrsch PB (May 1990). "Amino acid sequence of spinach chloroplast fructose-1,6-bisphosphatase". Archives of Biochemistry and Biophysics. 279 (1): 151–7. doi:10.1016/0003-9861(90)90475-E. PMID2159755.
^Marcus F, Gontero B, Harrsch PB, Rittenhouse J (Mar 1986). "Amino acid sequence homology among fructose-1,6-bisphosphatases". Biochemical and Biophysical Research Communications. 135 (2): 374–81. doi:10.1016/0006-291X(86)90005-7. PMID3008716.
