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The Dieckmann condensation, where a molecule with two ester groups reacts intramolecularly, forming a cyclic β-keto ester. In this case, the ring formed must not be strained, usually a 5- or 6-membered chain or ring. Retro-Claisen condensation is the reverse of the title reaction, i.e., the base-induced cleavage of 2-ketoesters
The glyoxylate cycle is a variant of the citric acid cycle. [4] It is an anabolic pathway occurring in plants and bacteria utilizing the enzymes isocitrate lyase and malate synthase. Some intermediate steps of the cycle are slightly different from the citric acid cycle; nevertheless oxaloacetate has the same function in both processes. [1]
ATP citrate lyase catalyses the Mg.ATP-dependent, CoA-dependent cleavage of citrate into oxaloacetate and acetyl-CoA, a key step in the reductive tricarboxylic acid pathway of CO 2 assimilation used by a variety of autotrophic bacteria and archaea to fix carbon dioxide. [4] ATP citrate lyase is composed of two distinct subunits.
They generally form by the Claisen condensation. The presence of the keto group at the beta position allows them to easily undergo thermal decarboxylation. [7] Gamma-keto acids, Gamma-ketoacids, or 4-oxoacids have the ketone group at the third carbon from the carboxylic acid. Levulinic acid is an example.
Malate, in the mitochondrial matrix, can be used to make pyruvate (catalyzed by malic enzyme) or oxaloacetic acid, both of which can enter the citric acid cycle. Glutamine can also be used to produce oxaloacetate during anaplerotic reactions in various cell types through "glutaminolysis", which is also seen in many c-Myc transformed cells. [3]
Citrate synthase has three key amino acids in its active site (known as the catalytic triad) which catalyze the conversion of acetyl-CoA [H 3 CC(=O)−SCoA] and oxaloacetate [− O 2 CCH 2 C(=O)CO 2 −] into citrate [− O 2 CCH 2 C(OH)(CO 2 −)CH 2 CO 2 −] and H−SCoA in an aldol condensation reaction. The citrate product is said to be ...
The reaction is known as the Claisen reaction and was described by Claisen for the first time in 1890. Discovered the thermally induced rearrangement of allyl phenyl ether in 1912. He details its reaction mechanism in his last scientific publication (1925). In his honor, the reaction has been named the Claisen rearrangement.
The reaction involving acetyl-CoA and succinate (EC 2.8.3.18) is part of a modified TCA cycle [4] or forms acetate during fermentation. [5] The reaction involving acetoacetate-CoA and succinate ( EC 2.8.3.5 ) degrades the ketone body acetoacetate formed during ketogenesis .