Regulatory Properties of Skeletal-Muscle Pyruvate Kinase

1977 ◽  
Vol 5 (6) ◽  
pp. 1747-1748
Author(s):  
BHANU ODEDRA ◽  
DENNIS P. BRILEY ◽  
ARTHUR W. G. COLE ◽  
T. NORMAN PALMER
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Muscle Pyruvate Kinase ◽  
Regulatory Properties

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 The regulatory properties of rabbit muscle pyruvate kinase. The influence of effector concentrations

1983 ◽  
Vol 209 (2) ◽  
pp. 413-415 ◽  
Author(s):  
R B Gregory ◽  
S Ainsworth ◽  
J Kinderlerer
Keyword(s):  
Pyruvate Kinase ◽  
Initial Velocity ◽  
Exponential Model ◽  
Rabbit Muscle ◽  
Muscle Pyruvate Kinase ◽  
Fructose 1,6 Bisphosphate ◽  
Regulatory Properties

The initial velocity of the reaction catalysed by rabbit muscle pyruvate kinase was studied as a function of the concentrations of the modifiers phenylalanine and fructose 1,6-bisphosphate under conditions where the relationships between the initial velocities and the concentrations of substrates are non-hyperbolic. It is shown that these data can be represented by the exponential model for a regulatory enzyme.

scholarly journals The regulatory properties of rabbit muscle pyruvate kinase. The influence of substrate concentrations

1983 ◽  
Vol 209 (2) ◽  
pp. 401-411 ◽  
Author(s):  
S Ainsworth ◽  
J Kinderlerer ◽  
R B Gregory
Keyword(s):  
Pyruvate Kinase ◽  
Exponential Model ◽  
Rabbit Muscle ◽  
Catalysed Reaction ◽  
Dead End ◽  
Influence Of Substrate ◽  
Muscle Pyruvate Kinase ◽  
Regulatory Properties ◽  
Kinetics Of ◽  
Substrate Concentrations

The kinetics of rabbit muscle pyruvate kinase were studied in assays at pH 7.4, where the relationships between the initial velocities of the catalysed reaction and the concentrations of substrates ADP, phosphoenolpyruvate and Mg2+ are non-hyperbolic. The data were used to test the applicability of the exponential model for a regulatory enzyme, which has been here extended to describe the behaviour of a three-substrate enzyme. It appears that the data can be represented by the model and as a result permit the conclusion that the substrates influence one another's binding by the same type of charge interactions that are evident in the Michaelis-Menten kinetics of the enzyme observed at pH 6.2. Evidence is also presented indicating that MgADP acts as a dead-end inhibitor of the enzyme at pH 7.4.

L-Phenylalanine inhibition of muscle pyruvate kinase

1982 ◽  
Vol 2 (10) ◽  
pp. 825-833 ◽  
Author(s):  
T. Norman Palmer ◽  
Bhanu R. Odedra
Keyword(s):  
Skeletal Muscle ◽  
Kinetic Analysis ◽  
Pyruvate Kinase ◽  
Competitive Inhibitor ◽  
Allosteric Inhibition ◽  
Reaction Velocity ◽  
Muscle Pyruvate Kinase ◽  
Regulatory Significance

The allosteric inhibition of Ml-type pyruvate kinase from rabbit skeletal muscle by phenylalanine is reciprocally dependent on Mg2+ and phosphoenolpyruvate concentrations. At pH 8, phenylalanine acts as a competitive inhibitor with respect to Mg2+ and phosphoenolpyruvate, and vice versa. Phenylalanine introduces sigmoidicity into the dependence of the reaction velocity on [Mg2+]. In vitro kinetic analysis indicates that phenylalanine inhibition of muscle pyruvate kinase is unlikely to have regulatory significance in vivo.

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