chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, a compartment is a part of a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that serves a specific function. They are essentially

protein subunits In structural biology, a protein subunit is a polypeptide chain or single protein molecule that assembles (or "''coassembles''") with others to form a protein complex. Large assemblies of proteins such as viruses often use a small number of ty ...

with the added condition that a compartment has distinct functionality, rather than being just a structural component. There may be multiple compartments on one and the same protein. One example is the case of

Pyruvate dehydrogenase complex Pyruvate dehydrogenase complex (PDC) is a complex of three enzymes that converts pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and t ...

. This is the enzyme which catalyses

Pyruvate decarboxylation Pyruvate decarboxylation or pyruvate oxidation, also known as the link reaction (or oxidative decarboxylation of pyruvate), is the conversion of pyruvate into acetyl-CoA by the enzyme complex pyruvate dehydrogenase complex. The reaction may be s ...

, the reaction of Pyruvate with Coenzyme A and the major entry point into the

TCA cycle The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and protein ...

: :Pyruvate + Coenzyme A + NAD⁺ ⇒ acetyl-CoA + NADH + H⁺ + CO₂

Pyruvate dehydrogenase Pyruvate dehydrogenase is an enzyme that catalyzes the reaction of pyruvate and a lipoamide to give the acetylated dihydrolipoamide and carbon dioxide. The conversion requires the coenzyme thiamine pyrophosphate. Pyruvate dehydrogenase is us ...

has three chemical compartments; E1 ( pyruvate decarboxylase), E2 (

dihydrolipoyl transacetylase Dihydrolipoyl transacetylase (or dihydrolipoamide acetyltransferase) is an enzyme component of the multienzyme pyruvate dehydrogenase complex. The pyruvate dehydrogenase complex is responsible for the pyruvate decarboxylation step that links glyco ...

) and E3 ( dihydrolipoyl dehydrogenase). Each one of the compartments has its own specific function.

References

Molecular biology {{biochemistry-stub