How is FAD described as part of succinate dehydrogenase?

FAD, or flavin adenine dinucleotide, is considered a prosthetic group in the context of succinate dehydrogenase because it is tightly bound to the enzyme and plays an essential role in its function. This binding is more than just transient; FAD remains physically associated with the enzyme during the catalytic process, thereby facilitating the conversion of succinate to fumarate in the citric acid cycle.

Being a prosthetic group means that FAD is an integral part of the enzyme structure and is necessary for its enzymatic activity, distinguishing it from coenzymes that may associate with enzymes more loosely and are often recycled during reactions. Therefore, the description of FAD as a prosthetic group highlights its integral and enduring role in the enzymatic mechanism of succinate dehydrogenase, contributing to its function in cellular respiration.