Activities, intracellular localization and kinetic properties of phosphoenolpyruvate carboxykinase, pyruvate kinase and malate dehydrogenase in turtle (Pseudemys scripta elegans) liver, heart and skeletal muscle

1973 ◽  
Vol 46 (2) ◽  
pp. 405-415 ◽  
Author(s):  
David G. Penney ◽  
Elizabeth H. Kornecki
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Malate Dehydrogenase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Intracellular Localization ◽  
Kinetic Properties ◽  
Pseudemys Scripta

scholarly journals Isoform expression in the multiple soluble malate dehydrogenase of Hoplias malabaricus (Erythrinidae, Characiformes)

2003 ◽  
Vol 63 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. R. Aquino-Silva ◽  
M. L. B. Schwantes ◽  
A. R. Schwantes
Keyword(s):  
Skeletal Muscle ◽  
Malate Dehydrogenase ◽  
Tandem Duplication ◽  
Carbon Flow ◽  
Substrate Affinity ◽  
Kinetic Properties ◽  
Thermal Stabilities ◽  
Hoplias Malabaricus ◽  
Isoform Expression

Kinetic properties and thermal stabilities of Hoplias malabaricus liver and skeletal muscle unfractionated malate dehydrogenase (MDH, EC 1.1.1.37) and its isolated isoforms were analyzed to further study the possible sMDH-A* locus duplication evolved from a recent tandem duplication. Both A (A1 and A2) and B isoforms had similar optima pH (7.5-8.0). While Hoplias A isoform could not be characterized as thermostable, B could as thermolabile. A isoforms differed from B isoform in having higher Km values for oxaloacetate. The possibly duplicated A2 isoform showed higher substrate affinity than the A1. Hoplias duplicated A isoforms may influence the direction of carbon flow between glycolisis and gluconeogenesis.

In vivo effect of Trigonella foenum graecum on the expression of pyruvate kinase, phosphoenolpyruvate carboxykinase, and distribution of glucose transporter (GLUT4) in alloxan-diabetic rats

2006 ◽  
Vol 84 (6) ◽  
pp. 647-654 ◽  
Author(s):  
Sameer Mohammad ◽  
Asia Taha ◽  
Kamal Akhtar ◽  
R.N.K. Bamezai ◽  
Najma Zaheer Baquer
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Plasma Glucose ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Transporter ◽  
Diabetic Rats ◽  
Altered Expression ◽  
Glucose Levels ◽  
Glucose Transporter Glut4

Plasma glucose levels are maintained by a precise balance between glucose production and its use. Liver pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), 2 key enzymes of glycolysis and gluconeogenesis, respectively, play a crucial role in this glucose homeostasis along with skeletal muscle glucose transporter (GLUT4). In the diabetic state, this balance is disturbed owing to the absence of insulin, the principal factor controlling this regulation. In the present study, alloxan-diabetic animals having high glucose levels of more than 300 mmol/L have been taken and the administration of Trigonella seed powder (TSP) to the diabetic animals was assessed for its effect on the expression of PK and PEPCK in liver and GLUT4 distribution in skeletal muscle of alloxan-diabetic rats. TSP treatment to the diabetic animals resulted in a marked decrease in the plasma glucose levels. Trigonella treatment partially restored the altered expression of PK and PEPCK. TSP treatment also corrected the alterations in the distribution of GLUT4 in the skeletal muscle.

Some kinetic properties of skeletal muscle pyruvate kinase from air-breathing and water-breathing fish of the Amazon

1978 ◽  
Vol 56 (4) ◽  
pp. 751-758 ◽  
Author(s):  
J. H. A. Fields ◽  
W. R. Driedzic ◽  
C. J. French ◽  
P. W. Hochachka
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Kinetic Properties ◽  
Air Breathing ◽  
Hoplias Malabaricus ◽  
Arapaima Gigas ◽  
Saturation Kinetics ◽  
Muscle Pyruvate Kinase ◽  
Hoplerythrinus Unitaeniatus

The kinetic properties of pyruvate kinase from skeletal muscle were studied in two species of air-breathing fish, Hoplerythrinus unitaeniatus and Arapaima gigas, and two species of water-breathing fish, Hoplias malabaricus and Osteoglossum bicirrhosum. It was found that the enzymes from Hoplias and Hoplerythrinus showed hyperbolic saturation kinetics for all substrates, were activated slightly by fructose 1,6-diphosphate, and were inhibited by phosphocreatine and citrate. The enzyme from Hoplias was inhibited by alanine, whereas the enzyme from Hoplerythrinus was not. The enzymes from Arapaima and Osteoglossum showed hyperbolic saturation kinetics for adenosine diphosphate, but the saturation kinetics for phusphoenol-pyruvate were sigmoidal. These enzymes were strongly activated by fructose 1,6-diphosphate and strongly inhibited by alanine, the former completely reversing the inhibition by the latter. Phosphocreatine and citrate were also found to be inhibitors of these enzymes, but the inhibition by phosphocreatine was not reversed by additions of fructose 1,6-diphosphate. The enzymes from the water-breathing fish were more sensitive to inhibition by alanine than were those from the air-breathing fish, but in other respects the enzymes were very similar.

Glyconeogenic pathway in isolated skeletal muscles of rats

2002 ◽  
Vol 80 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Analúcia Rampazzo Xavier ◽  
José Eduardo de Salles Roselino ◽  
Neusa Maria Zanon Resano ◽  
Maria Antonieta Rissato Garófalo ◽  
Renato Helios Migliorini ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Muscle Glycogen ◽  
Skeletal Muscles ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Metabolic Flux ◽  
Maximal Activity ◽  
Reverse Direction ◽  
Long Time ◽  
Muscle Pyruvate Kinase

Although the conversion of lactate to glycogen (glyconeogenesis) in muscle was demonstrated a long time ago, the biochemical reactions responsible for this process are still a controversial matter. In the present study, advantage was taken from the specific inhibition induced by phenylalanine on muscle pyruvate kinase (PK) to investigate the role of reverse PK activity in muscle glyconeogenesis. Addition of phenylalanine to the incubation medium of a preparation of isolated, intact skeletal muscles that maintain metabolic activity for several hours reduced by 50% the rate of incorporation of [14C]lactate or [14C]bicarbonate into muscle glycogen. Muscle extracts presented high levels of maximal activity of PK in the reverse direction, which was completely blocked in the presence of phenylalanine. In contrast, mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), did not affect the incorporation of14C from either lactate or bicarbonate into muscle glycogen. Maximal PEPCK activity was much lower in muscle extracts than in gluconeogenic or glyceroneogenic tissues and was suppressed in the presence of mercaptopicolinic acid. The data suggest that a reversal of the metabolic flux through the reaction catalyzed by PK contributes to the accumulation of lactate-derived glycogen that occurs in skeletal muscle under certain physiological conditions.Key words: lactate, glyconeogenesis, skeletal muscle, reverse pyruvate kinase reaction, phenylalanine.

scholarly journals Comparison of the properties of two forms of pyruvate kinase in rat liver and determination of their separate activities during development

1972 ◽  
Vol 127 (4) ◽  
pp. 721-731 ◽  
Author(s):  
Marshall C. Middleton ◽  
Deryck G. Walker
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Rat Liver ◽  
Developmental Period ◽  
Late Gestation ◽  
Kinetic Properties ◽  
Foetal Rat ◽  
Neonatal Liver ◽  
Developing Rat

1. Two forms of hepatic pyruvate kinase, designated type L and type M, were distinguished on the basis of kinetic, chromatographic, electrophoretic and immunological criteria. They were partially purified and their properties compared with each other and with the purified enzyme from skeletal muscle. 2. In contrast with type L, the type M enzyme showed no marked evidence of co-operative interactions with phosphoenolpyruvate and was not stimulated by fructose diphosphate. 3. The activity profiles of type L and type M enzymes were determined in developing rat liver by utilizing differences in the kinetic properties of the two forms. The high activity of type M enzyme in the early foetal rat decreased in late gestation and immediately after birth to reach a low value, which remained essentially constant for the remainder of the developmental period. The activity of type L enzyme, in contrast, was low in the early foetal and neonatal liver but increased markedly at the onset of weaning. 4. Possible roles of the two forms of hepatic pyruvate kinase in the control of glycolysis and gluconeogenesis are discussed.

scholarly journals Properties of pyruvate kinase and phosphoenolpyruvate carboxykinase in relation to the direction and regulation of phosphoenolpyruvate metabolism in muscles of the frog and marine invertebrates

1978 ◽  
Vol 174 (3) ◽  
pp. 979-987 ◽  
Author(s):  
Victor A. Zammit ◽  
Eric A. Newsholme
Keyword(s):  
Pyruvate Kinase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Marine Invertebrates ◽  
Adductor Muscle ◽  
Sea Anemone ◽  
Anaerobic Conditions ◽  
Fructose Bisphosphate ◽  
Low Concentrations ◽  
Optimum Ph ◽  
Hill Coefficients

1. The properties of pyruvate kinase and, if present, phosphoenolpyruvate carboxykinase from the muscles of the sea anemone, scallop, oyster, crab, lobster and frog were investigated. 2. In general, the properties of pyruvate kinase from all muscles were similar, except for those of the enzyme from the oyster (adductor muscle); the pH optima were between 7.1 and 7.4, whereas that for oyster was 8.2; fructose bisphosphate lowered the optimum pH of the oyster enzyme from 8.2 to 7.1, but it had no effect on the enzymes from other muscles. Hill coefficients for the effect of the concentration of phosphoenolpyruvate were close to unity in the absence of added alanine for the enzymes from all muscles except oyster adductor muscle; it was 1.5 for this enzyme. Alanine inhibited the enzyme from all muscles except the frog; this inhibition was relieved by fructose bisphosphate. Low concentrations of alanine were very effective with the enzyme from the oyster (50% inhibition was observed at 0.4mm). Fructose bisphosphate activated the enzyme from all muscles, but extremely low concentrations were effective with the oyster enzyme (0.13μm produced 50% activation). 3. In general, the properties of phosphoenolpyruvate carboxykinase from the sea anemone and oyster muscles are similar: the Km values for phosphoenolpyruvate are low (0.10 and 0.13mm); the enzymes require Mn2+ in addition to Mg2+ for activity; and ITP inhibits the enzymes and the inhibition is relieved by alanine. These latter compounds had no effect on enzymes from other muscles. 4. It is suggested that changes in concentrations of fructose bisphosphate, alanine and ITP produce a coordinated mechanism of control of the activities of pyruvate kinase and phosphoenolpyruvate carboxykinase in the sea anemone and oyster muscles, which ensures that phosphoenolpyruvate is converted into oxaloacetate and then into succinate in these muscles under anaerobic conditions. 5. It is suggested that in the muscles of the crab, lobster and frog, phosphoenolpyruvate carboxykinase catalyses the conversion of oxaloacetate into phosphoenolpyruvate. This may be part of a pathway for the oxidation of some amino acids in these muscles.

scholarly journals Influence of rapid changes in cytosolic pH on oxidative phosphorylation in skeletal muscle: theoretical studies

2002 ◽  
Vol 365 (1) ◽  
pp. 249-258 ◽  
Author(s):  
Bernard KORZENIEWSKI ◽  
Jerzy A. ZOLADZ
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Oxidative Phosphorylation ◽  
Kinetic Properties ◽  
Main Role ◽  
Anaerobic Glycolysis ◽  
Cytosolic Ph ◽  
Intensive Exercise ◽  
Proton Production ◽  
The Stability

Cytosolic pH in skeletal muscle may vary significantly because of proton production/consumption by creatine kinase and/or proton production by anaerobic glycolysis. A computer model of oxidative phosphorylation in intact skeletal muscle developed previously was used to study the kinetic effect of these variations on the oxidative phosphorylation system. Two kinds of influence were analysed: (i) via the change in pH across the inner mitochondrial membrane and (ii) via the shift in the equilibrium of the creatine kinase-catalysed reaction. Our simulations suggest that cytosolic pH has essentially no impact on the steady-state fluxes and most metabolite concentrations. On the other hand, rapid acidification/alkalization of cytosol causes a transient decrease/increase in the respiration rate. Furthermore, changes in pH seem to affect significantly the kinetic properties of transition between resting state and active state. An increase in pH brought about by proton consumption by creatine kinase at the onset of exercise lengthens the transition time. At intensive exercise levels this pH increase could lead to loss of the stability of the system, if not compensated by glycolytic H+ production. Thus our theoretical results stress the importance of processes/mechanisms that buffer/compensate for changes in cytosolic proton concentration. In particular, we suggest that the second main role of anaerobic glycolysis, apart from additional ATP supply, may be maintaining the stability of the system at intensive exercise.

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