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: The complexes formed by both carboxylating enzymes are thus similar to those found previously for muscle pyruvate kinase and, therefore, suggest homologous mechanisms for phosphoenolpyruVate carboxykinase, phosphoenlpyruvite carboxYkinase , and pyruve kinase.
166 citations
TL;DR: Metabolic pathways of the intermediate metabolism of maize root tips were identified and quantified after labeling to isotopic and metabolic steady state using glucose labeled on carbon-1, −2, or −6 with 14C or 13C and revealed the operation of the pentose phosphate pathway.
166 citations
TL;DR: In this article, the regulatory properties of Escherichia coli were investigated by mutating six charged residues involved in interdomain salt bridges (Arg271, Arg292, Asp297, and Lys413) and in binding of the allosteric activator (Lys382 and Arg431).
166 citations
TL;DR: High-fat feeding leads to selective upregulation of PDK4 expression in slow-twitch muscle in response to high-Fat feeding in vivo, which is associated with a pronounced loss of sensitivity ofPDK activity to acute inhibition by pyruvate.
Abstract: In using Western blot analysis with antibodies raised against recombinant pyruvate dehydrogenase kinase (PDK) isoforms PDK2 and PDK4, this study demonstrates selective PDK isoform switching in specific skeletal muscle types in response to high-fat feeding that is associated with altered regulation of PDK activity by pyruvate. The administration of a diet high in saturated fats led to stable (approximately 2-fold) increases in PDK activities in both a typical slow-twitch (soleus [SOL]) muscle and a typical fast-twitch (anterior tibialis [AT]) muscle. Western blot analysis revealed that high-fat feeding significantly increased (approximately 2-fold; P < 0.001) PDK4 protein expression in SOL, with a modest (1.3-fold) increase in PDK2 protein expression. The relative increase in PDK4 protein expression in SOL was associated with a 7.6-fold increase in the pyruvate concentration that was required to elicit a 50% active pyruvate dehydrogenase complex, which indicates a marked decrease in the sensitivity of PDK to inhibition by pyruvate. In AT muscle, high-fat feeding elicited comparable (1.5- to 1.7-fold) increases (P < 0.05) in PDK4 and PDK2 protein expression. Loss of sensitivity of PDK to inhibition by pyruvate was less marked. The data suggest that a positive correlation exists between increases in PDK4 expression and the propensity with which muscles use lipid-derived fuels as respiratory substrates rather than with the degree of insulin resistance induced in skeletal muscles by high-fat feeding. In conclusion, high-fat feeding leads to selective upregulation of PDK4 expression in slow-twitch muscle in response to high-fat feeding in vivo, which is associated with a pronounced loss of sensitivity of PDK activity to acute inhibition by pyruvate. Thus, increased PDK4 expression may underlie the stable modification of the regulatory characteristics of PDK observed in slow-twitch muscle in response to high-fat feeding.
166 citations
TL;DR: The biological significance of the inhibition of the key glycolytic enzymes is interpreted as a feedback inhibitory mechanism in regulation of fatty acid biosynthesis and may function for rapid adaptation by which the organism can use the fatty acid level as a metabolic directional switch in decreasing glyCOlysis and turning on gluconeogenesis.
Abstract: Increasing concentrations of sodium octanoate were progressively inhibitory to the activities of glucokinase, hexokinase, phosphofructokinase, and pyruvate kinase. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases were also markedly inhibited. Other enzymes of carbohydrate metabolism such as lactate dehydrogenase, phosphohexose isomerase, and fructose-1,6-diphosphatase were not decreased. Among the key glycolytic enzymes, the inhibition of pyruvate kinase by the fatty acid was most marked. The biological significance of the inhibition of the key glycolytic enzymes is interpreted as a feedback inhibitory mechanism in regulation of fatty acid biosynthesis. The mechanism may function for rapid adaptation by which the organism can use the fatty acid level as a metabolic directional switch in decreasing glycolysis and turning on gluconeogenesis.
166 citations