Phosphofructokinase is a kinase enzyme that phosphorylates fructose 6-phosphate in glycolysis. The enzyme-catalysed transfer of a phosphoryl group from ATP is an important reaction in a wide variety of biological processes. One enzyme that utilizes this reaction is phosphofructokinase (PFK), which catalyses the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate, a key regulatory step in the glycolytic pathway. PFK exists as a homotetramer in bacteria and mammals (where each monomer possesses 2 similar domains) and as an octomer in yeast (where there are 4 alpha-(PFK1) and 4 beta-chains (PFK2), the latter, like the mammalian monomers, possessing 2 similar domains[3]). This protein may use the morpheein model of allosteric regulation.http://www.creative-enzymes.com/product/Native-Bacillus-Stearothermophilus-Phosphofructokinase_1692.html