Reaction
The two molecules joined by acetyl-CoA synthetase are acetate and coenzyme A (CoA). The complete reaction with all the substrates and products included is:
- ATP + Acetate + CoA <=> AMP + Pyrophosphate + Acetyl-CoA
Once acetyl-CoA is formed it can be used in the TCA cycle in aerobic respiration to produce energy and electron carriers. This is an alternate method to starting the cycle, as the more common way is producing acetyl-CoA from pyruvate through the pyruvate dehydrogenase complex. The enzyme’s activity takes place in the mitochondrial matrix so that the products are in the proper place to be used in the following metabolic steps. Acetyl Co-A can also be used in fatty acid synthesis, and a common function of the synthetase is to produce acetyl Co-A for this purpose.
The reaction catalyzed by acetyl-CoA synthetase takes place in two steps. First, AMP must be bound by the enzyme to cause a conformational change in the active site, which allows the reaction to take place. The active site is referred to as the A-cluster. A crucial lysine residue must be present in the active site to catalyze the first reaction where Co-A is bound. Co-A then rotates in the active site into the position where acetate can covalently bind to CoA. The covalent bond is formed between the sulfur atom in Co-A and the central carbon atom of acetate.
The ACS1 form of acetyl-CoA synthetase is encoded by the gene facA, which is activated by acetate and deactivated by glucose.
Read more about this topic: Acetyl-Co A Synthetase
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