Kinetics of 6-phosphofructo-1-kinase from a yeast mutant.
The steady state kinetics of 6-phosphofructo-1-kinase was determined in a cell-free extract obtained from a yeast mutant (DFY 250) and compared with the kinetic properties of the enzyme of a wild-type strain (DFY 1). 6-Phosphofructo-1-kinase from the DFY 250 strain shows a complex kinetic behaviour, which is qualitatively similar to, but quantitatively different from, that of normal yeast 6-phosphofructo-1-kinase. The mutant enzyme has a lower affinity to its activators fructose 6-phosphate, fructose 2,6-bisphosphate and AMP. The inhibiting effect of ATP on the mutant 6-phosphofructo-1-kinase is substantially weaker than on the wild-type enzyme. A complex interaction between fructose 6-phosphate and fructose 2,6-bisphosphate at the 6-phosphofructo-1-kinase from strain DFY 250 is reflected by a remarkable substrate inhibition by fructose 6-phosphate even at saturating fructose 2,6-bisphosphate. The kinetic data were fitted to different variants of the Monod-Wyman-Changeux model by nonlinear regression analysis. It turned out that the influence of fructose 6-phosphate, ATP, AMP and fructose 2,6-bisphosphate on the activity of 6-phosphofructo-1-kinase from wild-type and DFY 250 strain could be described by rate equations of essentially the same structure.
Bigl
M
M
Institute of Biochemistry, University of Leipzig, FRG.
Eschrich
K
K
Hofmann
E
E
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D005635:Fructosediphosphates / Q000378:metabolism; D005636:Fructosephosphates / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
D005635:Fructosediphosphates; D005636:Fructosephosphates; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; C027618:fructose-6-phosphate; C027652:fructose 2,6-diphosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1