scholarly journals Acute regulation of pyruvate kinase activity in rat epididymal adipose tissue by insulin

1979 ◽  
Vol 180 (3) ◽  
pp. 523-531 ◽  
Author(s):  
R M Denton ◽  
N J Edgell ◽  
B J Bridges ◽  
G P Poole
Keyword(s):  
Pyruvate Kinase ◽  
Kinase Activity ◽  
Covalent Modification ◽  
Epididymal Adipose Tissue ◽  
Pyruvate Kinase Activity ◽  
Marked Diminution ◽  
Fructose 1,6 Bisphosphate ◽  
Fat Pads

1. Evidence is presented that exposure of epididymal fat-pads from fed rats to insulin leads to a marked diminution in the Km for phosphoenolpyruvate of pyruvate kinase. Effects of insulin may be readily demonstrated in experiments both in vivo and in vitro and are not secondary to the activation by the hormone of glucose transport. No effect of insulin is apparent in tissues from 48 h-starved animals. 2. The mechanism of the effect of insulin on pyruvate kinase was not established. The observed changes in Km do not appear to be the result of alterations in the amounts of bound effectors such as fructose 1,6-bisphosphate and alanine. Rather, as the effect persists in incubated extracts, it appears that a change in the degree of phosphorylation or some other covalent modification of the enzyme may be involved.

scholarly journals Adipose-tissue pyruvate kinase. Properties and interconversion of two active forms

1968 ◽  
Vol 110 (1) ◽  
pp. 67-77 ◽  
Author(s):  
C I Pogson
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Pyruvate Kinase ◽  
Kinase Activity ◽  
Deae Cellulose ◽  
Epididymal Adipose Tissue ◽  
Partial Purification ◽  
Pyruvate Kinase Activity ◽  
Bivalent Cation

1. Extraction of rat epididymal adipose tissue with buffer containing EDTA yields a pyruvate kinase, provisionally called PyK-A, the properties of which resemble in several respects those of the allosteric pyruvate kinase of liver. These properties include co-operative interactions with phosphoenolpyruvate, Mg2+, K+, NH4+ and ATP, and sensitivity to activation by fructose 1,6-diphosphate. 2. Extraction in the absence of EDTA yields predominantly a form, PyK-B, that shows both normal Michaelis–Menten kinetics with phosphoenolpyruvate, Mg2+ and ATP, and co-operative interactions with K+ and NH4+; this form is insensitive towards fructose 1,6-diphosphate. 3. Both forms yield simple kinetics with ADP, though Km values differ in the two systems. In all cases where co-operativity has been demonstrated, Hill-plot n values are between 1·4 and 2·0. 4. The conversion of PyK-A into PyK-B is mediated specifically by fructose 1,6-diphosphate; the reverse reaction is occasioned by EDTA, ATP or citrate. It is thought that a bivalent cation may be involved in this interconversion. 5. Attempts at partial purification have revealed that the enzyme resembles the pyruvate kinase of skeletal muscle, rather than that of liver, in its solubility in ammonium sulphate and elution from DEAE-cellulose. 6. The relevance of these properties in the regulation of pyruvate kinase activity in vivo in adipose tissue is discussed.

scholarly journals Characterization of yeast pyruvate kinase 1 as a protein kinase A substrate, and specificity of the phosphorylation site sequence in the whole protein

2006 ◽  
Vol 396 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Paula Portela ◽  
Silvia Moreno ◽  
Silvia Rossi
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Pyruvate Kinase ◽  
Phosphorylation Site ◽  
Bovine Heart ◽  
Specificity Constant ◽  
Fructose 1,6 Bisphosphate ◽  
Kinase A

Pyk1 (pyruvate kinase 1) from Saccharomyces cerevisiae was characterized as a substrate for PKA (protein kinase A) from bovine heart and yeast. By designing Pyk1 synthetic peptides containing potential PKA sequence targets (Ser22, Thr94 and Thr478) we determined that the peptide S22 was a substrate for PKA in vitro, with a Ksp* (specificity constant) 10-fold and 3-fold higher than Kemptide for bovine heart and yeast PKA respectively. In vitro phosphorylation of the Pyk1 S22A mutant protein was decreased by as much as 90% when compared with wild-type Pyk1 and the Pyk1 T94A mutant. The Ksp* values for Pyk1 and Pyk1 T94A were the same, indicating that both proteins are phosphorylated at the same site by PKA. Two-dimensional PAGE of Pyk1 and Pyk1 S22A indicates that in vivo the S22A mutation prevented the formation of one of the Pyk1 isoforms. We conclude that in yeast the major PKA phosphorylation site of Pyk1 is Ser22.Phosphorylation of Ser22 leads to a Pyk1 enzyme that is more active in the absence of FBP (fructose 1,6-bisphosphate). The specificity of yeast and mammalian PKA towards the S22 peptide and towards whole Pyk1 protein was measured and compared. The Ksp* for the S22 peptide is higher than that for Pyk1, indicating that the peptide modelled on Pyk1 is a much better substrate than Pyk1, regardless of which tissue was used as the source of PKA. However, the Km of Pyk1 protein is lower than that of the better substrate, the S22 peptide, indicating that ground-state substrate binding is not the major determinant of substrate specificity for PKA.

scholarly journals Lead inhibits in vitro creatine kinase and pyruvate kinase activity in brain cortex of rats

2010 ◽  
Vol 24 (3) ◽  
pp. 1045-1051 ◽  
Author(s):  
Tatiana Wannmacher Lepper ◽  
Evandro Oliveira ◽  
Gustavo Duarte Waltereith Koch ◽  
Daiane Bolzan Berlese ◽  
Luciane Rosa Feksa
Keyword(s):  
Creatine Kinase ◽  
Pyruvate Kinase ◽  
Brain Cortex ◽  
Kinase Activity ◽  
Pyruvate Kinase Activity

scholarly journals Development of gluconeogenesis from dihydroxyacetone in rat hepatocytes during a feeding cycle and starvation

1984 ◽  
Vol 218 (3) ◽  
pp. 975-981 ◽  
Author(s):  
B Azzout ◽  
J Peret
Keyword(s):  
Catalytic Activity ◽  
Pyruvate Kinase ◽  
Kinase Activity ◽  
Activity Ratio ◽  
Rat Hepatocytes ◽  
Equal Proportion ◽  
Pyruvate Kinase Activity ◽  
Nocturnal Feeding ◽  
Feeding Cycle ◽  
Fructose 1,6 Bisphosphate

Pyruvate kinase activity and the rates of gluconeogenesis and glycolysis in rat hepatocytes were evaluated by production of glucose and lactate + pyruvate from dihydroxyacetone during a feeding cycle or progressive starvation. In fed rats, during daylight (low food intake) and until darkness, gluconeogenesis progressively increased and glycolysis decreased slightly, but gluconeogenesis never exceeded glycolysis. During nocturnal feeding, gluconeogenesis and glycolysis returned to their morning rates. After 8 h starvation, an equal proportion of dihydroxyacetone was converted into glucose and into lactate + pyruvate. When glycogen was depleted (11 h of starvation), gluconeogenesis was maximal and glycolysis minimal. In fed and starved rats, the concentration of fructose 1,6-bisphosphate was the same. The activity ratio of pyruvate kinase (ratio of velocity at 0.5 mM-phosphoenolpyruvate to the maximum catalytic activity obtained with 4mM-phosphoenolpyruvate) was high in crude extracts of cells incubated with dihydroxyacetone and low in (NH4)2SO4-treated extracts, but remained unchanged during the whole experiment. There was no correlation between the rates of gluconeogenesis and glycolysis from dihydroxyacetone and the activity ratio of pyruvate kinase.

scholarly journals AG-348 enhances pyruvate kinase activity in red blood cells from patients with pyruvate kinase deficiency

Blood ◽  
2017 ◽  
Vol 130 (11) ◽  
pp. 1347-1356 ◽  
Author(s):  
Charles Kung ◽  
Jeff Hixon ◽  
Penelope A. Kosinski ◽  
Giovanni Cianchetta ◽  
Gavin Histen ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Pyruvate Kinase ◽  
Blood Cells ◽  
Kinase Activity ◽  
Red Cell ◽  
Pyruvate Kinase Activity ◽  
Pyruvate Kinase Deficiency ◽  
Key Points ◽  
Allosteric Activator

Key Points AG-348 is a small-molecule allosteric activator of WT red cell pyruvate kinase as well as mutant enzymes associated with hemolytic anemia. Activity in vitro, in mice, and in red blood cells suggests it may address the underlying molecular pathology in PK deficiency patients.

Effect of L-Histidine on Human and Rat Jejunal Pyruvate Kinase Activity

1971 ◽  
Vol 49 (10) ◽  
pp. 1105-1116 ◽  
Author(s):  
Fred B. Stifel ◽  
Robert H. Herman
Keyword(s):  
Pyruvate Kinase ◽  
Inverse Relationship ◽  
Kinase Activity ◽  
Progressive Increase ◽  
Pyruvate Kinase Activity ◽  
Deficient Diet ◽  
Feeding Groups ◽  
Regulation Of Glycolysis ◽  
Complete Diet

L-Histidine was found to be an in vitro activator of both human and rat jejunal pyruvate kinase activity and rat hepatic pyruvate kinase activity. Jejunal and hepatic pyruvate kinase activities were higher in rats fed a histidine-complete diet than a histidine-deficient diet. Feeding groups of rats successively larger doses of oral histidine produced a progressive increase in rat jejunal pyruvate kinase activity. An inverse relationship was seen between the pyruvate kinase activity without histidine added and the percent stimulation with histidine added in vitro.The histidine effect appears to be a ubiquitous one in the rat, since stimulation was observed in each of the seven tissues tested. The broad range of the histidine effect suggests that it may play a fundamental role in the regulation of glycolysis in mammalian systems.

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.

Red blood cell age, pyruvate kinase activity, and insulin receptors. Evidence that monocytes and RBCs may behave differently

Diabetes ◽  
1983 ◽  
Vol 32 (11) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Camagna ◽  
R. De Pirro ◽  
L. Tardella ◽  
L. Rossetti ◽  
R. Lauro ◽  
...  
Keyword(s):  
Blood Cell ◽  
Pyruvate Kinase ◽  
Red Blood Cell ◽  
Kinase Activity ◽  
Insulin Receptors ◽  
Pyruvate Kinase Activity ◽  
Cell Age

Red Blood Cell Age, Pyruvate Kinase Activity, and Insulin Receptors: Evidence that Monocytes and RBCs May Behave Differently

Diabetes ◽  
1983 ◽  
Vol 32 (11) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Camagna ◽  
R. D. Pirro ◽  
L. Tardella ◽  
L. Rossetti ◽  
R. Lauro ◽  
...  
Keyword(s):  
Blood Cell ◽  
Pyruvate Kinase ◽  
Red Blood Cell ◽  
Kinase Activity ◽  
Insulin Receptors ◽  
Pyruvate Kinase Activity ◽  
Cell Age
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