title: Regulation of glycolysis in sea bass liver: phosphofructokinase isozymes.
abstract: Sea bass (Dicentrarchus labrax L.) liver phosphofructokinase (PFK) presents biphasic kinetics with respect to fructose-6-phosphate (F-6-P) in experiments carried out with crude extract. After the enzyme had been purified, two isozymes have been detected after chromatographic treatment. The two isozymes present different kinetic behaviour PFK-L1, the first eluted phosphofructokinase activity shows positive cooperativity with respect to fructose-6-phosphate and PFK-L2, the second activity fraction, has a Hill coefficient of 0.38 (negative cooperativity). The first isozyme shows less affinity for fructose-6-phosphate than that shown by PFK-L2. The joint kinetics of both isozymes produces a biphasic kinetics with respect to fructose-6-phosphate, similar to that observed in crude extracts.
authors.affiliation: Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: Fideu
authors.forename: M L
authors.initials: ML
authors.lastname: Pérez
authors.forename: M J
authors.initials: MJ
authors.lastname: Herranz
authors.forename: M
authors.initials: M
authors.lastname: Ruiz-Amil
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D001492:Bass / Q000378:metabolism*; D005636:Fructosephosphates / Q000378:metabolism; D006019:Glycolysis; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D010473:Perciformes / Q000378:metabolism*; D010732:Phosphofructokinase-1 / Q000302:isolation & purification / Q000378:metabolism*; D013696:Temperature
chemical_list: D005636:Fructosephosphates; D007527:Isoenzymes; C027618:fructose-6-phosphate; D010732:Phosphofructokinase-1