Citric acid cycle component

Citric acid cycle components (from rat heart mitochondria). 

Citric acid cycle components (from rat heart mitochondria). Resolved by anion-exchange chromatography [LaNoue et al. JBC 245 102 1970]. 

Citric Acid Cycle Components Are Important Biosynthetic Intermediates... 

Compartmentalization of Citric Acid Cycle Components Isocitrate dehydrogenase is found only in the mitochondrion, but malate dehydrogenase is found in both the cytosol and mitochondrion. What is the role of cytosolic malate dehydrogenase ... 

Synthesizing a-ketoglutarate. It is possible, with the use of the reactions and enzymes discussed in this chapter, to convert pyruvate into a-ketoglutarate without depleting any of the citric acid cycle components. Write a balanced reaction scheme for this conversion, showing cofactors and identifying the required enzymes. 

The citric acid cycle is the central metabolic hub of the cell. It is the gateway to the aerobic metabolism of any molecule that can be transformed into an acetyl group or a component of the citric acid cycle. The cycle is also an important source of precursors for the building blocks of many other molecules such as amino acids, nucleotide bases, and porphyrin (the organic component of heme). The citric acid cycle component, oxaloacetate. is also an important precursor to glucose (p. 460). 

Sodium fluoroacetate is a controversial poison also known as Compound 1080. When an isolated rat heart is perfused with sodium fluoroacetate, the rate of glycolysis decreases and hexose monophosphates accumulate. In cardiac cells, fluoroacetate is condensed with oxaloacetate to give fluorocitrate. Under these conditions, cellular citrate concentrations increase, while the levels of other citric acid cycle components decrease. What enzyme is inhibited by fluorocitrate How can you account for the decrease in glycolysis and the buildup of hexose monophosphates ... 

It was first observed that adrenal homogenates and crudely fractionated particles require or can be activated by various cofactors and combinations of cofactors and metabolic intermediates, such as glucose, fumarate and other citric acid cycle components, adenosine triphosphate (ATP) or adenylic acid, nicotinamide or diphospho-pyridine nucleotide (DPN) (334,386,570,721) or triphosphopyridine nucleotide (TPN) in place of DPN plus ATP (335,786). The activity of meticulously prepared adrenal mitochondria is inhibited by low concentrations of dinitrophenol it was therefore suggested that lljS-hydroxylation requires concurrent oxidative phosphorylation (112,386). 

The cofactor requirement of lljS-hydroxylase was clarified by the discovery that reduced triphosphopyridine nucleotide (TPNH) is essential and specific and that the role of citric acid cycle components and the other cofactors in the system appears to be that of supplying endogenously formed TPNH (288,723) by the sequence of reactions shown in equations (98) to (100). TPNH is oxidized in the absence... 

Von Korff, R. W. (1969), Ion-exchange chromatography of citric acid cycle components and related compounds. Methods EnzymoL, 13,425-430. 

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