Topic
Pyruvate dehydrogenase kinase
About: Pyruvate dehydrogenase kinase is a research topic. Over the lifetime, 4224 publications have been published within this topic receiving 161052 citations. The topic is also known as: [pyruvate dehydrogenase (lipoamide)] kinase & pyruvate dehydrogenase (lipoamide) kinase.
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TL;DR: In cell extracts of both strains, pyruvate dehydrogenase activity dependent on thiamine pyrophosphate, coenzyme A, and NAD was shown, and there was higher activity in aerobically growing cells than in anaerobically grown cells.
Abstract: Streptococcus mutans NCTC 10449 and Escherichia coli K-12 strain 37 were grown under aerobic and anaerobic conditions. In cell extracts of both strains, pyruvate dehydrogenase activity dependent on thiamine pyrophosphate, coenzyme A, and NAD was shown. The enzyme was induced by pyruvate in the growth medium, and there was higher activity in aerobically grown cells than in anaerobically grown cells. Acetyl phosphate was a potent inhibitor of the activity. This inhibition was partly overcome by inorganic phosphate.
57 citations
TL;DR: The current results support the idea that carboxylation of glucose-derived pyruvate, as well as decarboxylating of pyruVate, is important for glucose-induced insulin secretion.
57 citations
TL;DR: The data suggest that pyruvate transport may control gluconeogenesis from L-lactate and that hormones may stimulate this process through an effect on the respiratory chain and an additional role for pyruVate kinase and pyruviate carboxylase is quite compatible with the data presented.
Abstract: The sensitivity of glucose production from L-lactate by isolated liver cells from starved rats to inhibition by alpha-cyano-4-hydroxycinnamate was studied. A small percentage of the maximal rate of gluconeogenesis was insensitive to inhibition by alpha-cyano-4-hydroxycinnamate, and evidence is presented to show that this is due to pyruvate entry into the mitochondria as alanine. After subtraction of this rate, Dixon plots of the reciprocal of the rate of gluconeogenesis against inhibitor concentration were linear both in the absence and presence of glucagon, phenylephrine or valinomycin, each of which stimulated gluconeogenesis by 30-50%. Pyruvate kinase activity was decreased by glucagon, but not by phenylephrine or valinomycin. Inhibition of gluconeogenesis by quinolinate (inhibitor of phosphoenolpyruvate carboxykinase) or monochloroacetate (probably inhibiting pyruvate carboxylation) caused a significant deviation from linearity of the Dixon plot obtained with alpha-cyano-4-hydroxycinnamate. Amytal, however, inhibited gluconeogenesis without affecting the linearity of this plot. These data, coupled with a computer simulation study, suggest that pyruvate transport may control gluconeogenesis from L-lactate and that hormones may stimulate this process through an effect on the respiratory chain. An additional role for pyruvate kinase and pyruvate carboxylase is quite compatible with the data presented.
57 citations
TL;DR: Although no changes in islet PPar-alpha expression were observed after the starvation protocol, activation of PPAR-alpha in vivo may be a potential mechanism underlying upregulation of islet PDK4 protein expression in starvation.
Abstract: The pyruvate dehydrogenase complex (PDC) has a pivotal role in islet metabolism. The pyruvate dehydrogenase kinases (PDK1–4) regulate glucose oxidation through inhibitory phosphorylation of PDC. Starvation increases islet PDK activity (AmJ Physiol Endocrinol Metab 270:E988–E994, 1996). In this study, using antibodies against PDK1, PDK2, and PDK4 (no sufficiently specific antibodies are as yet available for PDK3), we identified the PDK isoform profile of the pancreatic islet and delineated the effects of starvation (48 h) on protein expression of individual PDK isoforms. Rat islets were demonstrated to contain all three PDK isoforms, PDK1, PDK2, and PDK4. Using immunoblot analysis with antibodies raised against the individual recombinant PDK isoforms, we demonstrated increased islet protein expression of PDK4 in response to starvation (2.3-fold; P
57 citations
TL;DR: The formation of acetyl-CoA from pyruvate required ATP; kinetic evidence as well as experiments with [γ-32P]ATP indicated that this serves as an activator and not as a substrate in the reaction.
57 citations