6-Phosphofructo-2-kinase and fructose-2,6-bisphosphatase from Saccharomyces cerevisiae.
In permeabilized yeast cells 6-phosphofructo-2-kinase and fructose-2,6-bisphosphatase are studied during growth. It is shown that in yeast at least two fructose 2,6-bisphosphate degrading enzyme activities occur, differing in pH profile and in their substrate affinities. The activities of 6-phosphofructo-2-kinase and of fructose-2,6-bisphosphatases drop in the exponential and the transition phase while the activity of the alkaline phosphatases steadily increases. In the stationary phase the activities of 6-phosphofructo-2-kinase and of the low Km fructose-2,6-bisphosphatase increase again. Yeast 6-phosphofructo-2-kinase and fructose-2,6-bisphosphatase were purified and separated from each other. The purified 6-phosphofructo-2-kinase was found to exhibit a very high specific activity (1.3 U/mg). The enzyme is efficiently inhibited by ATP. The ATP inhibition is most pronounced at low concentrations of magnesium and fructose-6-phosphate. Phosphoenolpyruvate and sn-glycerol 3-phosphate are inhibitors of the enzyme. The high-affinity yeast fructose-2,6-bisphosphatase releases inorganic phosphate from the 2-position of fructose 2,6-bisphosphate. It displays hyperbolic kinetics towards fructose 2,6-bisphosphate (Km = 0.3 microM) and is strongly inhibited by fructose 6-phosphate. The inhibition is counteracted by sn-glycerol 3-phosphate. The enzyme is shown to be inactivated by cAMP-dependent phosphorylation and reactivated by the action of protein phosphatase 2A.
Hofmann
E
E
Institute of Biochemistry, Karl-Marx-University Leipzig, German Democratic Republic.
Bedri
A
A
Kessler
R
R
Kretschmer
M
M
Schellenberger
W
W
D002463:Cell Membrane Permeability; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development
D046911:Macromolecular Substances; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases