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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TL;DR: An enzymatic method for determing serum triglycerides (triacylglycerols) is described, adapted to a centrifugal analyzer, and yields satisfactory results with regard to precision, accuracy, and insensitivity to interferences.
Abstract: I describe an enzymatic method for determing serum triglycerides (triacylglycerols). The triglycerides are hydrolyzed by a mixture of lipase and esterase. The glycerol released is determined by kinetic fixed-time analysis, with use of glycerol kinase, pyruvate kinase, and lactate dehydrogenase. Through addition of the competitive inhibitor ATP the Michaelis constant of pyruvate kinase is apparently increased, considerably extending the linearity of the assay. There is no need for serum blanks or reagent blanks. The method has been adapted to a centrifugal analyzer (the ENI GEMSAEC). It yields satisfactory results with regard to precision, accuracy, and insensitivity to interferences.
58 citations
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TL;DR: G glycogen and glucose, formed during B. microplus embryogenesis after blastoderm formation, are produced by intense gluconeogenesis, as well as phosphoenolpyruvate carboxykinase activities after embryo cellularization.
Abstract: Glucose metabolism plays an essential role in the physiology and development of almost all living organisms. In the present study we investigated glucose metabolism during the embryogenesis of the hard tick Boophilus microplus. An increase in glucose and glycogen content during the embryonic development of B. microplus was detected and shown to be due to the high enzyme activity of both gluconeogenesis and glycolytic pathways. Glucose 6-phosphate (G-6P), formed by hexokinase, is driven mainly to pentose-phosphate pathway, producing fundamental substrates for cellular biosynthesis. We detected an increase in glucose 6-phosphate dehydrogenase and pyruvate kinase activities after embryo cellularization. Accumulation of key metabolites such as glycogen and glucose was monitored and revealed that glycogen content decreases from day 1 up to day 6, as the early events of embryogenesis take place, and increases after the formation of embryo cellular blastoderm on day 6. Glucose and guanine (a sub-product of amino acids degradation in arachnids) accumulate almost concomitantly. The activity of phosphoenolpyruvate carboxykinase was increased after embryo cellularization. Taken together these data indicate that glycogen and glucose, formed during B. microplus embryogenesis after blastoderm formation, are produced by intense gluconeogenesis.
58 citations
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TL;DR: The results show that the PK-deficient cell is heterogeneously affected by whatever mechanisms induce its destruction, and a population of "young" PK cells contains more seriously damaged cells than apopulation of older cells, the latter living to an older age because of their improved initial outlook.
Abstract: To define the role of the spleen in the hemolytic anemia associated with erythrocyte pyruvate kinase (PK) deficiency, removal rates and patterns or organ sequestration of 51Cr-labeled PK erythrocytes were studied. Recipients were the PK patients themselves, normal subjects and persons splenectomized for diverse causes. In one study the 51Cr was attached to "young" and "old" populations of PK erythrocytes before their injection; in another the "young" population was differentially labeled with glycine-2–14C. The results show that the PK-deficient cell is heterogeneously affected by whatever mechanisms induce its destruction. Therefore, a population of "young" PK cells contains more seriously damaged cells than a population of older cells, the latter living to an older age because of their improved initial outlook. Younger cells, if they pass through the spleen, are subsequently destroyed in the liver. Removal of the spleen improves the survival of the younger cells, for they are then destroyed muc...
58 citations
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TL;DR: It is proposed that K+ induces the closure of the active site and the arrangement of the residues involved in the binding of the nucleotide that allows either phosphoenolpyruvate or ADP to bind independently (random mechanism) in the absence of K+.
58 citations
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TL;DR: The results indicate that ADP generated by the mitochondrially bound enzyme is at least partially sequestered and directed toward the mitochondrial oxidative phosphorylation apparatus, and suggested dependence on an intramitochondrial pool (or pools) of ATP during active oxidativeosphorylation.
57 citations