Citrate synthase location

Mammalian citrate synthase is a dimer of identical 49-kd subunits. Each active site is located in a cleft between the large and small domains of a subunit, adjacent to the subunit interface. The results of x-ray crystallographic studies of citrate synthase and its complexes with several substrates and inhibitors revealed that the enzyme undergoes large conformational changes in the course of catalysis. Citrate synthase exhibits sequential, ordered... 

The main purpose of the glyoxylate cycle (Figure 12.7) which is located in glyoxysomes of plants is the synthesis of succinate from which carbohydrate may be produced. The reaction sequence utilizes organelle-specific isoenzymes of three enzymes of the tricarboxylate cycle citrate synthase, aconitate hydratase and malate dehydrogenase. These enzymes together with two enzymes... 

During the formation of carboxylic acid like lA, there will be shuttling of metabolites within the intracellular compartments, having the capability to utilize the enzymes of the respective compartments. Jaklitsch et al. (1991) reported that the CadA, which is e key enzyme for the biosynthesis of lA, is located in cytosol. Otiier important enzymes, such as citrate synthase and aconitase, are found in the mitochondria, but some residual level of these enzymes are also found in the cytosolic fraction. The depicted mechanism is that the ds-aconitate is transported to cytosol assisted by the malate-citrate antiporter. The biosynthetic pathway of LA in the citric acid cycle is illustrated in Fig. 10.5. 

We already mentioned that the enzymes involved in the P-oxidation of fatty acids are located in the mitochondria. The source of two-carbon fragments for the biosynthesis of both fatty acids and isoprenoids like cholesterol is acetyl CoA, which is generated by oxidative metabolism in the mitochondria. Acetyl CoA cannot escape from the mitochondria, but it can be exported to the cyosol as citrate, where it is reconverted to oxaloacete and acetyl CoA. Fatty acid (and cholesterol) biosynthesis takes place in the cyosol, and requires bicarbonate, which is incorporated into acetyl CoA to form malonyl CoA by acetyl CoA carboxylase. The biosynthesis of fatty acids, mostly the Cie palmitate (Chapter 4), requires one molecule of acetyl CoA and seven molecules of malonyl CoA. In animals, the seven enzymatic reactions which are required for fatty acid synthesis are present in a single multifunctional protein complex, known as fatty acid synthase. The synthase also contains an acyl-carrier protein... 

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