How do cofactors and coenzymes function in enzyme catalysis?

Cofactors and coenzymes assist enzymes in catalysing reactions by providing necessary functional groups or aiding in substrate binding.

Cofactors are non-protein molecules that bind to enzymes and assist in catalysis. They can be either inorganic, such as metal ions, or organic, such as heme. Inorganic cofactors often act as electron carriers, while organic cofactors can provide functional groups that are necessary for catalysis. For example, the cofactor biotin is necessary for the carboxylation of pyruvate in gluconeogenesis.

Coenzymes are organic molecules that are required for enzyme activity, but are not permanently bound to the enzyme. They often act as carriers of functional groups or electrons, such as NAD+ and FAD, which carry electrons in redox reactions. Coenzymes can also aid in substrate binding, such as the coenzyme ATP, which helps enzymes bind to their substrates.

Overall, cofactors and coenzymes play crucial roles in enzyme catalysis by providing necessary functional groups or aiding in substrate binding. Without these molecules, many enzyme-catalysed reactions would not occur efficiently, if at all.