Final answer:
Pyruvate decarboxylase catalyzes the decarboxylation of pyruvate to acetaldehyde, releasing CO₂ in the process. It uses thiamine pyrophosphate as a coenzyme and is not a hydrolase or isomerase but rather a decarboxylase, which is a type of lyase.
Step-by-step explanation:
Pyruvate decarboxylase is an enzyme that catalyzes the conversion of pyruvate to acetaldehyde and carbon dioxide (CO₂). This process is known as a decarboxylation reaction because it involves the removal of a carboxyl group (CO₂) from the pyruvic acid molecule. Consequently, this transforms pyruvate, a three-carbon molecule, into acetaldehyde, which has two carbons.
Pyruvate decarboxylase requires a coenzyme, specifically thiamine pyrophosphate (TPP), which is derived from vitamin B₁. This step is crucial in fermentation, particularly in yeast, where it leads to the production of ethanol found in alcoholic beverages. The ethanol tolerance of yeast is an important factor in this process, as it can limit the alcohol levels that can be produced during fermentation.
As pyruvate decarboxylase removes a carboxyl group from pyruvate, it is not classified as a hydrolase or isomerase. Instead, it is more accurately described as a lyase, specifically a decarboxylase, because it breaks bonds by means other than hydrolysis or oxidation, without the addition of water.