Pyruvate kinase

About: Pyruvate kinase is a research topic. Over the lifetime, 5683 publications have been published within this topic receiving 180020 citations. The topic is also known as: ATP:pyruvate 2-O-phosphotransferase & phosphoenolpyruvate kinase.

Extreme hemolysis and red-cell distortion in erythrocyte pyruvate kinase deficiency. i. morphology, erythrokinetics and family enzyme studies.

Abstract: IN a preceding paper1 the clinical, morphologic, enzymatic and erythrokinetic abnormalities attending the violent chronic hemolytic anemia of M.P., a child with homozygous pyruvate kinase deficiency, were described. The following discussion deals with certain disturbances of the metabolism of his erythrocytes that appear to contribute to the mechanisms of hemolysis in this disorder. The data are also of broader interest because they may afford additional insight into the general mechanisms of the death of erythrocytes in man. Materials and Methods In vitro studies of the patient's erythrocyte potassium flux, potassium and water contents, glucose consumption and adenosine triphosphate (ATP) stability . . .

Glycolytic flux in Zymomonas mobilis: enzyme and metabolite levels during batch fermentation.

Abstract: The rate at which Z. mobilis (Entner-Doudoroff pathway) converts high concentrations of glucose (20%) into ethanol plus CO2 changes as ethanol accumulates in the surrounding broth. This decline in glycolytic activity (per milligram of cell protein) does not result from inhibitory effects of ethanol, which can be reversed immediately by ethanol removal. The peak of fermentative activity (58 mumol of CO2 evolved per mg of cell protein per h) occurred after the accumulation of 1.1% ethanol (18 h) and declined to one-half this rate after 30 h (6.2% accumulated ethanol), although the cell number continued to increase. These times corresponded to the end of exponential growth and to the onset of the stationary phase (on the basis of measurement of cell protein), respectively. An examination of many of the requirements for fermentation (nucleotides, magnesium, enzyme levels, intracellular pH, delta pH) revealed three possible reasons for this early decline in activity: decreased abundance of nucleotides, a decrease in internal pH from 6.3 to 5.3, and a decrease in the specific activities of two glycolytic enzymes (pyruvate kinase and glyceraldehyde-3-phosphate dehydrogenase). 31P nuclear magnetic resonance spectra of perchlorate extracts from cells fermenting in broth revealed very low levels of glycolytic intermediates (Entner-Doudoroff pathway) in cells examined at the peak of fermentative activity (18-h cells) in comparison with cells examined at a later stage (30-h cells), consistent with limitation of the fermentation rate by glycolytic enzymes near the end of the pathway. It is likely that cell death (loss of colony-forming ability) and the collapse of delta pH also contribute to the further decline in fermentative activity after 30 h.

A comparison of the properties of the phosphofructokinases of the fat body and flight muscle of the adult male desert locust

Abstract: 1. The pyruvate kinases of the desert locust fat body and flight muscle were partially purified by ammonium sulphate fractionation. 2. The fat-body enzyme is allosterically activated by very low (1μm) concentrations of fructose 1,6-diphosphate, whereas the flight-muscle enzyme is unaffected by this metabolite at physiological pH. 3. Flight-muscle pyruvate kinase is activated by preincubation at 25° for 5min., whereas the fat-body enzyme is unaffected by such treatment. 4. Both enzymes require 1–2mm-ADP for maximal activity and are inhibited at higher concentrations. With the fat-body enzyme inhibition by ADP is prevented by the presence of fructose 1,6-diphosphate. 5. Both enzymes are inhibited by ATP, half-maximal inhibition occurring at about 5mm-ATP. With the fat-body enzyme ATP inhibition can be reversed by fructose 1,6-diphosphate. 6. The fat-body enzyme exhibits maximal activity at about pH7·2 and the activity decreases rapidly above this pH. This inactivation at high pH is not observed in the presence of fructose 1,6-diphosphate, i.e. maximum stimulating effects of fructose 1,6-diphosphate are observed at high pH. The flight-muscle enzyme exhibits two optima, one at about pH7·2 as with the fat-body enzyme and the other at about pH8·5. Stimulation of the enzyme activity by fructose 1,6-diphosphate was observed at pH8·5 and above.

Control of Glycolysis and Glycogen Metabolism

Abstract: The sections in this article are: 1 Importance of Glycolysis in Skeletal Muscle at Rest and During Exercise 2 General Overview of the Glycolytic Pathway 2.1 ATP Supply 2.2 Support of Other Metabolic Needs 3 Properties of Glycogen and Associated Enzymes 3.1 Structure of Glycogen 3.2 Control of GP 3.3 Control of GS 3.4 Integrated Control of GP and GS During Exercise 4 Other Specific Glycolytic Enzyme Controls 4.1 Equilibrium Group 4.2 Phosphofructokinase 4.3 Aldolase 4.4 Glyceraldehydephosphate Dehydrogenase and Phosphoglycerate Kinase (PGK) 4.5 Phosphoglycerate Mutase and Enolase 4.6 Pyruvate Kinase 4.7 Lactate Dehydrogenase 5 Carbohydrate Utilization at Rest and During Exercise 5.1 Diurnal Variations of Body Stores at Rest 5.2 CHO Utilization during Exercise 5.3 Control of Glycogenolysis during Heavy Exercise 6 Postexercise Glycogen Synthesis and its Control 6.1 Resynthesis of Muscle Glycogen After Exercise 6.2 Regulatory Mechanisms 7 Muscle Glycogen Metabolism and Fatigue 7.1 Importance of CHO during Prolonged Exercise 7.2 Importance of Glycogen during High-Intensity Exercise 8 Integrative Aspects of Glycolytic Control and Future Directions (K. Sahlin) 8.1 Rest-Work Transition 8.2 Future Directions 9 Integrative Aspects of Glycolytic Control and Future Directions (R. J. Connett) 9.1 Systems Analysis 9.2 Cellular Oxygen Tension and Lactate Formation 9.3 Summary 9.4 State of the Phosphate Energy System 9.5 Cytosolic pH 9.6 Substrate Effects 9.7 Future Directions