Pyruvate dehydrogenase phosphate

C.F., Oswald, A. S., Shen, T.Y., Kinter, M., Tang, G.Z., and Zeller, K. Rat liver insulin mediator which stimulates pyruvate dehydrogenase phosphate contains galactosamine and D-chiroinositol. Biochem. Biophys. Res. Commun., 1988, 151, 1416-1426. 

Pyruvate dehydrogenase phosphate phosphatase is stimulated by Ca. In muscles, the Ca + concentration increases dramatically during muscle contraction. How would the elevated Ca + concentration affect the rate of glycolysis and the citric acid cycle ... 

A cell is deficient in pyruvate dehydrogenase phosphate phosphatase. How would such a deficiency affect cellular metabolism ... 

ATP is an important source of energy for muscle contraction. Pyruvate dehydrogenase phosphate phosphatase is activated by calcium ion, which increases greatly in concentration during exercise. Why is activation of the phosphatase consistent veith the metabolic requirements of muscle during contraction ... 

Pyruvic and lactic acids Pyruvate decarboxylase EC4.1.1.1) Pyruvate dehydrogenase phosphate phosphatase (EC 1.2.3.3), Dihydrolipoyl dehydrogenase (ECl.6.4.3) 15.4... 

Several enzymes of the intermediary metabolism require thiaminpyrophosphate (TPP, Fig. 1) as coenzyme, e.g., enzymes of the pyruvate dehydrogenase complex, a-ketoglutarate dehydrogenase complex, or pentose phosphate pathway. 

Insulin stimulates lipogenesis by several other mechanisms as well as by increasing acetyl-CoA carboxylase activity. It increases the transport of glucose into the cell (eg, in adipose tissue), increasing the availability of both pyruvate for fatty acid synthesis and glycerol 3-phosphate for esterification of the newly formed fatty acids, and also converts the inactive form of pyruvate dehydrogenase to the active form in adipose tissue but not in liver. Insulin also—by its ability to depress the level of intracellular cAMP—inhibits lipolysis in adipose tissue and thereby reduces the concentration of... 

ATP-proton motive force interconversion Electron transport Entner-Doudoroff Fermentation Glycolysis/gluconeogenesis Pentose phosphate pathway Pyruvate dehydrogenase Sugars TCA cycle Methanogenesis Polysaccharides Other... 

Many enzymes in the mitochondria, including those of the citric acid cycle and pyruvate dehydrogenase, produce NADH, aU of which can be oxidized in the electron transport chain and in the process, capture energy for ATP synthesis by oxidative phosphorylation. If NADH is produced in the cytoplasm, either the malate shuttle or the a-glycerol phosphate shuttle can transfer the electrons into the mitochondria for delivery to the ETC. Once NADH has been oxidized, the NAD can again be used by enzymes that require it. 

Figure 16.1 The glucose/fatty add cycle. The dotted Lines represent regulation. Glucose in adipose tissue produces glycerol 3-phosphate which enhances esterification of fatty acids, so that less are available for release. The effect is, therefore, tantamount to inhibition of lipolysis. Fatty acid oxidation inhibits pyruvate dehydrogenase, phosphofructokinase and glucose transport in muscle (Chapters 6 and 7) (Randle et al. 1963).

This enzyme [EC 2.7.1.99] catalyzes the reaction of ATP with [pyruvate dehydrogenase (lipoamide)] to produce ADP and [pyruvate dehydrogenase (lipoamide)] phosphate. This is an enzyme that is associated with the pyruvate dehydrogenase complex. Phosphorylation of pyruvate dehydrogenase (lipoamide) [EC 1.2.4.1] inactivates that enzyme. 

Fig. 1. Energy metabolism in the normal myocardium (ATP adenosine-5 -triphosphate, ADP adenosine-5 -diphosphate, P phosphate, PDH pyruvate dehydrogenase complex, acetyl-CoA acetyl-coenzyme A, NADH and NAD" nicotinamide adenine dinucleotide (reduced and oxidized), FADH2 and FAD flavin adenine dinucleotide (reduced and oxidized).

Fig.3.8.3 Oxygen uptake by intact (a) and digitonin-permeabilized (b) fibroblasts. I-V Respiratory chain complexes I-V, AcCoA acetylcoenzyme A, BSA bovine serum albumin, CCP carbonyl cyanide m-chlorophenylhydrazone, Cit citrate, CoA coenzyme A, CS citrate synthase, Dig digitonin, Fo FI the ATPase components, Fum fumarase, G3P glycerol-3-phosphate, im inner membrane, Mai malate, Malo malonate, MDH malate dehydrogenase, OAA oxaloacetate, om outer membrane, PDH pyruvate dehydrogenase, Pi inorganic phosphate, Pyr pyruvate, Q ubiquinone, Rot rotenone, Succ succinate, t time...

NAD Pools and Dehydrogenase Activities Although both pyruvate dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase use NAD+ as their electron acceptor, the two enzymes do not compete for the same cellular NAD pool. Why ... 

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