Conversion of specific uridine residues to pseudouridine and the addition of methyl groups to the 2′-hydroxyl groups

of specific riboses, that are important for the proper assembly and function of snRNPs in pre-mRNA splicing. 

These modifications occur in Cajal bodies, where they are directed by a class of snoRNA-like guide RNA molecules called scaRNAs (small Cajal body–associated RNAs)

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#Unit 1. Molecules and their Interaction Relevant to Biology

Acetyl-CoA and NADH are potent allosteric inhibitors of the enzyme. 

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#Unit 1. Molecules and their Interaction Relevant to Biology

Acetyl-CoA inhibits the transacetylase component whereas NADH inhibits the dihydrolipoyl dehydrogenase component. 

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#Unit 1. Molecules and their Interaction Relevant to Biology

The reaction catalyzed by citrate synthase is essentially a Claisen condensation, involving a thioester (acetyl-CoA) and a ketone (oxaloacetate)

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#Unit 1. Molecules and their Interaction Relevant to Biology

Eukaryotic cells have two isozymes of aconitase

• The mitochondrial isozyme (convert citrate to isocitrate in the citric acid cycle)

• The cytosolic isozyme 

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#Unit 1. Molecules and their Interaction Relevant to Biology

The cytosolic isozymes has two distinct function, It catalyzes the conversion of citrate to isocitrate, providing the substrate for a cytosolic isocitrate dehydrogenase that generates NADPH as reducing power for fatty acid synthesis and other anabolic processes in the cytosol. It also has a role in cellular iron homeostasis

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#Unit 1. Molecules and their Interaction Relevant to Biology

When cellular iron concentrations return to normal levels, IRP1 is converted to aconitase, and IRP2 undergoes proteolytic degradation, ending the low-iron response.