Coenzymes

Coenzymes are small, non-protein organic molecules that certain enzymes cannot work without — whether they float freely, dissociating after each reaction, or sit firmly bound to their enzyme partner. They ferry chemical groups and electrons through metabolism: NAD carries hydrogen, coenzyme A carries acyl groups, and many B vitamins serve as coenzyme precursors. Without them, the protein machinery of the cell stalls. Food scientists meet coenzymes in fermentation biochemistry, in the vitamin fortification that keeps metabolic pathways running, and in assays where enzyme activity reports on food quality.