Topic
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.
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73 citations
Journal Article•
TL;DR: Tumors originating from each of the tissues studied contained mainly the fetal types of the three enzymes and lacked the adult forms, indicating a tendency for the molecular composition of the several kinds of neoplasms to resemble that of immature rat tissues.
Abstract: Electrophoretic analyses of the isoenzymes of lactate dehydrogenase, aldolase, and pyruvate kinase and chemical analyses of aldolase identified single forms of each that predominated in fetal rat tissues: lactate dehydrogenase 5 (M), aldolase A, and pyruvate kinase K. Other forms of one or more of these enzymes characterized the normal adult liver, kidney, skeletal muscle, and mammary gland tissues. A new finding was the appearance of the cathodic aldolase C in lactating mammary gland. Tumors originating from each of the tissues studied contained mainly the fetal types of the three enzymes and lacked the adult forms. The findings indicate a tendency for the molecular composition of the several kinds of neoplasms to resemble that of immature rat tissues.
73 citations
TL;DR: PEP synthase is the essential enzyme for the glycolytic conversion of PEP to pyruvate in T. kodakarensis, in contrast to the conventional EM pathway dependent on pyruVate kinase.
Abstract: We have carried out a genetic analysis on pyruvate kinase (PykTk) and phosphoenolpyruvate synthase (PpsTk) in the hyperthermophilic archaeon, Thermococcus kodakarensis. In principle, both enzymes can catalyse the final step of the modified Embden-Meyerhof (EM) pathway found in Thermococcales, the conversion of phosphoenolpyruvate (PEP) to pyruvate, with the former utilizing ADP, while the latter is dependent on AMP and phosphate. Enzyme activities and transcript levels of both PykTk and PpsTk increased in T. kodakarensis under glycolytic conditions when compared with cells grown on pyruvate or amino acids. Using KW128, a tryptophan auxotrophic mutant with a trpE gene disruption, as a host strain, we obtained mutant strains with single gene disruptions in either the pykTk (Deltapyk strain) or ppsTk (Deltapps strain) gene. Specific growth rates and cell yields were examined in various media and compared with the host KW128 strain. The results indicated that both enzymes participated in pyruvate metabolism, but were not essential. In the presence of maltooligosaccharides, the Deltapyk strain displayed a 15% decrease in growth rate compared with the host strain, indicating that PykTk does participate in glycolysis. However an even more dramatic effect was observed in the Deltapps strain in that the strain could not grow at all on maltooligosaccharides. The results clearly indicate that, in contrast to the conventional EM pathway dependent on pyruvate kinase, PEP synthase is the essential enzyme for the glycolytic conversion of PEP to pyruvate in T. kodakarensis. The physiological roles of the two enzymes under various growth conditions are discussed.
73 citations
TL;DR: The in vivo activity of PKc is probably regulated by the relative cytosolic levels of DHAP, Pi, and glutamate; this provides a rationale for the activation of algal cytosolsolic pyruvate kinase which occurs during periods of enhanced ammonia assimilation.
73 citations
TL;DR: Results show directly that under physiological conditions the major energy carrier from mitochondria into cytoplasm is PCr, produced by mitochondrial creatine kinase (MtCK), which functional coupling to adenine nucleotide translocase is enhanced by selective limitation of permeability of mitochondrial outer membrane within supercomplex ATP Synthasome-Mt CK-VDAC-tubulin, Mitochondrial Interactosome.
Abstract: The aim of this study was to measure energy fluxes from mitochondria in isolated permeabilized cardiomyocytes. Respiration of permeabilized cardiomyocytes and mitochondrial membrane potential were measured in presence of MgATP, pyruvate kinase - phosphoenolpyruvate and creatine. ATP and phosphocreatine concentrations in medium surrounding cardiomyocytes were determined. While ATP concentration did not change in time, mitochondria effectively produced phosphocreatine (PCr) with PCr/O(2) ratio equal to 5.68 +/- 0.14. Addition of heterodimeric tubulin to isolated mitochondria was found to increase apparent Km for exogenous ADP from 11 +/- 2 microM to 330 +/- 47 microM, but creatine again decreased it to 23 +/- 6 microM. These results show directly that under physiological conditions the major energy carrier from mitochondria into cytoplasm is PCr, produced by mitochondrial creatine kinase (MtCK), which functional coupling to adenine nucleotide translocase is enhanced by selective limitation of permeability of mitochondrial outer membrane within supercomplex ATP Synthasome-MtCK-VDAC-tubulin, Mitochondrial Interactosome.
73 citations