Cosubstrates are transiently bound to the protein and will be released at some point, then get back in. The prosthetic groups, on the other hand, are bound permanently to the protein. Both of them have the same function, which is to facilitate the reaction 2 types of cofactors in an enzyme enzymes and protein. Additionally, some sources also limit the use of the term “cofactor” to inorganic substances. Some enzymes or enzyme complexes require several cofactors.
It has been suggested that the AMP part of the molecule can be considered to be a kind of “handle” by which the enzyme can “grasp” the coenzyme to switch it between different catalytic centers. The term coenzyme refers specifically to enzymes and, as such, to the functional properties of a protein. Different sources give slightly different definitions of coenzymes, cofactors, and prosthetic groups. Some consider tightly bound organic molecules as prosthetic groups and not as coenzymes, while others define all non-protein organic molecules needed for enzyme activity as coenzymes, and classify those that are tightly bound as coenzyme prosthetic groups. These terms are often used loosely. However, the author could not arrive at a single all-encompassing definition of a “coenzyme” and proposed that this term be dropped from use in the literature. In many cases, the cofactor includes both an inorganic and organic component. Iron-sulfur clusters are complexes of iron and sulfur atoms held within proteins by cysteinyl residues. They play both structural and functional roles, including electron transfer, redox sensing, and as structural modules.
It is important to emphasize that there is no sharp division between loosely and tightly bound cofactors. Tightly bound cofactors are, in general, regenerated during the same reaction cycle, while loosely bound cofactors can be regenerated in a subsequent reaction catalyzed by a different enzyme. In the latter case, the cofactor can also be considered a substrate or cosubstrate. However, vitamins do have other functions in the body. Most of these cofactors are found in a huge variety of species, and some are universal to all forms of life. This common chemistry allows cells to use a small set of metabolic intermediates to carry chemical groups between different reactions.