Breakdown of Pyruvate


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This illustration shows the three-step conversion of pyruvate into acetyl upper case C lower case o upper case A. In step one, a carboxyl group is removed from pyruvate, releasing carbon dioxide. In step two, a redox reaction forms acetate and N A D H. In step three, the acetate is transferred coenzyme A, forming acetyl upper C lower o upper A.
Upon entering the mitochondrial matrix, a multi-enzyme complex converts pyruvate into acetyl CoA. In the process, carbon dioxide is released, and one molecule of NADH is formed.

Source: OpenStax Biology 2e

OpenStax Biology 2e

In order for pyruvate, the product of glycolysis, to enter the next pathway, it must undergo several changes. The conversion is a three-step process.

Step 1. A carboxyl group is removed from pyruvate, releasing a molecule of carbon dioxide into the surrounding medium. This reaction creates a two-carbon hydroxyethyl group bound to the enzyme (pyruvate dehydrogenase). We should note that this is the first of the six carbons from the original glucose molecule to be removed. (This step proceeds twice because there are two pyruvate molecules produced at the end of glycolsis for every molecule of glucose metabolized anaerobically; thus, two of the six carbons will have been removed at the end of both steps.)

– What is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group?

Step 2. The hydroxyethyl group is oxidized to an acetyl group, and the electrons are picked up by NAD+, forming NADH. The high-energy electrons from NADH will be used later to generate ATP.

Step 3. The enzyme-bound acetyl group is transferred to CoA, producing a molecule of acetyl CoA.

During the second stage of glucose metabolism, whenever a carbon atom is removed, it is bound to two oxygen atoms, producing carbon dioxide, one of the major end products of cellular respiration.

Pyruvate is a carboxylic acid produced by the metabolism of glucose. In 1990, Stanko and colleagues published two studies that involved upper and lower limb endurance capacity in individuals who consumed pyruvate. The results of these studies caught the eye of the supplement industry and pyruvate was aggressively marketed by companies as being performance enhancing for endurance events. The unproven mechanism was that pyruvate enhances glucose oxidation.


Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: