Effect of ginseng principle on pyruvate kinase activity in rat liver.

1979 ◽  
Vol 27 (2) ◽  
pp. 419-423 ◽  
Author(s):  
TAKAKO YOKOZAWA ◽  
NAMIKO KITAHARA ◽  
SHOKO OKUDA ◽  
HIKOKICHI OURA
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Pyruvate Kinase Activity

scholarly journals Regulation of rat liver pyruvate kinase. The effect of preincubation, pH, copper ions, fructose 1,6-diphosphate and dietary changes on enzyme activity

1968 ◽  
Vol 108 (3) ◽  
pp. 427-436 ◽  
Author(s):  
E. Bailey ◽  
F. Stirpe ◽  
C B Taylor
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Copper Ions ◽  
Maximal Activity ◽  
Pyruvate Kinase Activity ◽  
Significant Reversal ◽  
Sigmoidal Kinetics ◽  
Influence Of Ph ◽  
Allosteric Activator

1. Preincubation of partially purified rat liver L-type pyruvate kinase at 25° for 10min. causes a marked increase in co-operativity with respect to both the substrate, phosphoenolpyruvate, and the allosteric activator, fructose 1,6-diphosphate. 2. The results are consistent with the existence of two forms of liver L-type pyruvate kinase, designated forms LA and LB. It is postulated that form LA has a low Km for phosphoenolpyruvate (about 0·1mm) and is not allosterically activated, whereas form LB is allosterically activated by fructose 1,6-diphosphate, exhibiting in the absence of the activator sigmoidal kinetics with half-maximal activity at about 1mm-phosphoenolpyruvate. In the presence of fructose 1,6-diphosphate, form LB gives Michaelis–Menten kinetics with Km less than 0·1mm. It is further postulated that preincubation converts form LA into form LB. 3. The influence of pH on the preincubation effect was studied. 4. The inhibition of pyruvate kinase by Cu2+ was studied in detail. Though phosphoenolpyruvate and fructose 1,6-diphosphate readily protect the enzyme against Cu2+ inhibition, little evidence of significant reversal of the inhibition by these compounds could be found. 5. The effects of starvation, fructose feeding and preincubation on the pyruvate kinase activity of crude homogenates of various tissues of the rat were also studied.

Pyruvate kinase activity and gluconeogenesis in RAT liver after glycogen depletion with nicotinic acid

1976 ◽  
Vol 13 (2) ◽  
pp. 89-93 ◽  
Author(s):  
Francisco J. Moreno ◽  
Manuel Benito ◽  
Fermín Sánchez-Medina ◽  
José M. Medina ◽  
Federico Mayor
Keyword(s):  
Nicotinic Acid ◽  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Glycogen Depletion ◽  
Pyruvate Kinase Activity

scholarly journals Kinetic properties of rat liver pyruvate kinase at cellular concentrations of enzyme, substrates and modifiers

1974 ◽  
Vol 141 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Wayne Flory ◽  
Benigno D. Peczon ◽  
Roger E. Koeppe ◽  
H. Olin Spivey
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Enzyme Concentration ◽  
Kinetic Properties ◽  
Type I ◽  
Enzyme Properties ◽  
Pyruvate Kinase Activity ◽  
Enzyme Substrates ◽  
Cellular Control

Kinetic properties of rat liver pyruvate kinase type I at pH7.5 and 6.5 were studied with physiological ranges of substrates, modifiers and Mg2+ concentrations at increasing enzyme concentrations, including the estimated cellular concentrations (approx. 0.1mg/ml). Enzyme properties appear unaffected by increased enzyme concentration if phosphoenolpyruvate, fructose 1,6-diphosphate and inhibitors are incubated with enzyme before starting the reaction with ADP. Our data suggest that minimum cellular concentrations of MgATP and l-alanine provide virtually complete inhibition of pyruvate kinase I at pH7.5. The most likely cellular control of existing pyruvate kinase I results from the strong restoration of enzyme activity by the small physiological amounts of fructose 1,6-diphosphate. Decreasing the pH to 6.5 also restores pyruvate kinase activity, but to only about one-third of its activity in the presence of fructose 1,6-diphosphate. Neither pyruvate nor 2-phosphoglycerate at cellular concentrations inhibit the enzyme significantly.

scholarly journals The role of mitochondria in modifying calcium-sensitive cytoplasmic metabolic activities. Modification of pyruvate kinase activity

1972 ◽  
Vol 128 (2) ◽  
pp. 415-420 ◽  
Author(s):  
J. Meli ◽  
F. L. Bygrave
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Pyruvate Kinase Activity ◽  
Metabolic Activities ◽  
The One

1. The modification of pyruvate kinase activity in vitro was examined by altering the environmental [Mg2+]/[Ca2+] ratio with EDTA on the one hand and isolated rat liver mitochondria on the other. 2. Controlled additions of Ca2+ and EDTA caused pyruvate kinase activity to be alternately and rapidly switched on and off. 3. By being able to accumulate Ca2+ in preference to Mg2+ rat liver mitochondria were able to alter the [Mg2+]/[Ca2+] ratio in the vicinity of pyruvate kinase and thereby modify the activity of this enzyme. 4. The possible role of mitochondria in modifying pyruvate kinase and other ion-sensitive cytoplasmic enzyme activities is discussed.

scholarly journals Comparison of pyruvate kinase variants from rat liver and Morris hepatoma 7777, obtained by an affinity chromatography on blue sepharose CL-6B.

1993 ◽  
Vol 40 (2) ◽  
pp. 261-267 ◽  
Author(s):  
J Ignacak ◽  
M Gumińska
Keyword(s):  
Affinity Chromatography ◽  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Signal Molecules ◽  
Pyruvate Kinase Activity ◽  
Normal Rat ◽  
Morris Hepatoma ◽  
Blue Sepharose ◽  
Main Substrate

Fractions A (salted out by ammonium sulphate between 21-30% saturation), and fractions B (salted out between 51-70% saturation) of pyruvate kinase (EC 2.7.1.40.) corresponding respectively to pyruvate kinase types L and M2 from rat liver and Morris hepatoma 7777 were purified by an affinity chromatography on Blue Sepharose CL-6B. Peaks of inactive proteins were eliminated and the enzyme fractions bound biospecifically to the gels were eluted by free ADP. The molecular mass of purified hepatoma pyruvate kinase fraction B was smaller than that of liver pyruvate kinase fraction B. Morris hepatoma pyruvate kinase fraction B represented a variant of type M2, characterised by greatest affinity to 2-phosphoenolpyruvate as a main substrate and different sensitivity to low-molecular effectors in comparison with types L from both liver and hepatoma and in comparison with type M2 from normal rat liver. Only this hepatoma fraction B showed a tumour specific sensitivity to L-cysteine and was insensitive to normal signal molecules i.e. to ATP and fructose-1,6-diphosphate which influence liver pyruvate kinase activity. L-Cysteine inhibited the tumour fraction B of pyruvate kinase by decreasing its Vmax and increasing the Km values in relation to 2-phosphoenolpyruvate.

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