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.

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.

Air-breathing mechanics in two Amazonian teleosts, Arapaima gigas and Hoplerythrinus unitaeniatus

1978 ◽  
Vol 56 (4) ◽  
pp. 939-945 ◽  
Author(s):  
A. P. Farrell ◽  
D. J. Randall
Keyword(s):  
Gas Pressure ◽  
Breathing Patterns ◽  
Air Breathing ◽  
Arapaima Gigas ◽  
Breathing Mechanics ◽  
Replacement Technique ◽  
Hoplerythrinus Unitaeniatus

The mechanics of air breathing in pirarucu, Arapaima gigas, and jeju, Hoplerythrinus unitaeniatus, were studied by simultaneous monitoring of air bladder gas pressure and buccal pressure. Also the effect of alterations in air bladder gas tensions on air-breathing patterns was examined by a gas replacement technique. Pirarucu surface every 4.2 min to make a single ventilation of the air bladder, whilst jeju usually make two or three ventilations at an air breath every 3.0 min. Pirarucu exhale first, then inhale, but in jeju buccal filling occurred before lung emptying. Inhalation in pirarucu is a result of air bladder aspiration combined with the action of a buccal pump; however, lung filling in jeju is achieved by a buccal pump only. The significance of aspiration breathing in pirarucu is discussed. Both fish respond similarly to alterations in air bladder gas tensions. Hyperoxia prolongs the interval between air breaths and hypercapnia reduces this interval.

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.

Chemical and enzymatic characterization of recombinant rabbit muscle pyruvate kinase

2013 ◽  
Vol 394 (5) ◽  
pp. 695-701 ◽  
Author(s):  
Christian Boehme ◽  
Frank Bieber ◽  
Julia Linnemann ◽  
Reinhard Breitling ◽  
Stefan Lorkowski ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Transition Metal Ions ◽  
Recombinant Enzyme ◽  
High Yield ◽  
Rabbit Muscle ◽  
Reading Frame ◽  
Ph Range ◽  
Muscle Pyruvate Kinase

Abstract The stepwise synthesis of thymidine triphosphate (TTP) requires a kinase for phosphorylation in the last step. Because pyruvate kinase (PK) using phosphoenolpyruvate (PEP) as substrate can regenerate adenosine triphosphate and phosphorylate thymidine diphosphate as well, we chose this enzyme for the synthesis of TTP via an enzymatic cascade reaction. The metalloenzyme PK shows pronounced promiscuity and therefore fits well to the conditions of this reaction. PK commonly used today is isolated from rabbit muscle. We cloned and expressed the respective open reading frame in Escherichia coli, purified, and characterized the His-tagged recombinant enzyme. The enzyme has an activity optimum at 37°C and in the pH range from 7.4 to 7.8. Km constants conformed well with the isolated native enzyme for adenosine diphosphate (ADP) to 0.37±0.02 mm and for PEP to 0.07±0.01 mm. The recombinant enzyme shows the following range in its substrate specificity: ADP>dADP>dGDP>dCDP>thymidine diphosphate (TDP). It allows the phosphorylation of TDP to TTP in high yield (up to 95%). The metal ions Mg2+ and K+ are necessary for full enzymatic activity. The addition of transition metal ions such as Mn2+, Cu2+, Co2+, and Ni2+ reduces activity. Storage of the enzyme at -20°C retains full activity.

Gill phospholipids of Amazon fishes

1978 ◽  
Vol 56 (4) ◽  
pp. 793-794 ◽  
Author(s):  
Charles F. Phleger
Keyword(s):  
Phospholipid Composition ◽  
Hoplias Malabaricus ◽  
Arapaima Gigas ◽  
Hoplerythrinus Unitaeniatus

Gill phospholipid composition was quantitatively determined for four Amazon fishes. The fishes included Hoplias malabaricus (obligate water breather), Hoplerythrinus unitaeniatus and Erythrinus erythrinus (facultative air breathers), and Arapaima gigas (obligate air breather). Phosphatidylcholine and phosphatidylethanolamine were the principal gill phospholipids (49–64% and 12–27% of the total phospholipids, respectively). Other phospholipids present included sphingomyelin (5–16%), phosphatidylserine(1–13%), lysophosphatidylcholine (0–6%), phosphatidylinositol (0–5%), and diphosphatidylglycerol (0–3%). The gill phospholipid composition was similarfor these four species of fish.

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
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