title: Modification of yeast phosphofructokinase with pyridoxal 5'-phosphate.
abstract: Modification of yeast phosphofructokinase (E.C. 2.7.1.11) with pyridoxal 5'-phosphate leads to a decreased enzyme activity. ATP at higher concentrations protects the enzyme against inactivation, while fructose 6-phosphate has no effect. At relatively low concentrations of pyridoxal phosphate the inhibition of activity by ATP was decreased or even abolished. AMP still activates the modified enzyme pointing to a separate binding site in the regulatory centre. The dissociation of the phosphopyridoxyl enzyme in products with apparent sedimentation coefficients of about 4-6 S gives evidence that lysine might be involved in the stabilization of the quaternary structure of yeast phosphofructokinase. The incorporation of pyridoxal phosphate in the 17 S form of yeast phosphofructokinase as obtained by a partial proteolysis does not show differences from the 20 S, proteolytically unmodified enzyme.
mesh_terms: D004586:Electrophoresis; D007700:Kinetics; D008970:Molecular Weight; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D011489:Protein Denaturation; D011732:Pyridoxal Phosphate / Q000378:metabolism / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D011732:Pyridoxal Phosphate; D010732:Phosphofructokinase-1