Where does the conversion of pyruvate to Acetyl-CoA occur?

The conversion of pyruvate to Acetyl-CoA occurs in the mitochondria. This biochemical process, often referred to as pyruvate decarboxylation or the transition reaction, takes place within the mitochondrial matrix. During this conversion, one molecule of carbon dioxide is released, and the remaining two-carbon fragment is attached to coenzyme A, forming Acetyl-CoA.

This is a crucial step in cellular respiration, linking glycolysis (which occurs in the cytoplasm) to the Krebs cycle (also known as the citric acid cycle), which takes place in the mitochondria. The production of Acetyl-CoA from pyruvate is vital because Acetyl-CoA serves as a substrate for the Krebs cycle, where it is further oxidized to produce energy carriers like NADH and FADH2. Therefore, the mitochondrial environment is essential for this transformation to occur efficiently.