title: Phosphofructokinase from baker's yeast: kinetic properties of a proteolytically modified enzyme.
abstract: A tetrameric enzyme form of phosphofructokinase from yeast (called 12 S-enzyme), formed by limited proteolysis of the octameric enzyme in the presence of ATP and by subsequent dissociation in two half-molecules shows sigmoidal kinetics with respect to fructose 6-phosphate and inhibition by ATP. Similar to the native phosphofructokinase, the modified enzyme is also efficiently activated by AMP and fructose 2,6-bisphosphate. Both activators increase the affinity for the substrate fructose 6-phosphate and the respective maximum activity. In contrast to the native phosphofructokinase, however, both AMP and fructose 2,6-bisphosphate change the sigmoidal fructose 6-phosphate velocity curve into a hyperbolic one. AMP and fructose 2,6-bisphosphate decrease the ATP inhibition, probably by modulating the affinity of the allosteric sites to ATP.
authors.affiliation: Institut für Biochemie, Karl-Marx-Universität Leipzig, DDR.
authors.forename: J
authors.initials: J
authors.lastname: Bär
authors.forename: W
authors.initials: W
authors.lastname: Schellenberger
authors.forename: G
authors.initials: G
authors.lastname: Kopperschläger
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D004789:Enzyme Activation; D005636:Fructosephosphates / Q000378:metabolism; D007700:Kinetics; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D005636:Fructosephosphates; D000249:Adenosine Monophosphate; C027618:fructose-6-phosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1