Which compound acts as a prosthetic group and CO2 carrier in biochemical reactions?

Biotin is a crucial cofactor in various biochemical reactions, particularly as a carrier of carbon dioxide (CO2). It functions as a prosthetic group by forming stable covalent bonds with enzymes, specifically those involved in carboxylation reactions, where CO2 is incorporated into organic molecules. Biotin is essential in processes such as gluconeogenesis, fatty acid synthesis, and the metabolism of certain amino acids.

The role of biotin as a CO2 carrier is primarily seen in carboxylase enzymes, such as pyruvate carboxylase, which catalyze the conversion of pyruvate to oxaloacetate by adding a CO2 molecule to pyruvate. This ability to transport CO2 is vital for maintaining metabolic pathways that generate energy and synthesize biomolecules.

The other compounds listed, while important in metabolism, do not function as CO2 carriers. NAD+ and FADH2 are electron carriers involved in redox reactions, mainly serving functions in energy production pathways like glycolysis and the citric acid cycle, but they do not carry CO2. ATP is a primary energy currency of the cell, providing energy for various biochemical reactions, but it does not act as a CO2 carrier or a prosthetic group