deaminating

Deaminating is the process of removing an amino group from a molecule, typically an amino acid or nucleotide. In biochemistry, deamination most often refers to enzymatic removal of an amino group, producing a carbonyl-containing compound and free ammonia, and forming a key step in nitrogen metabolism and the redistribution of carbon skeletons.

In amino acid catabolism, deamination can be oxidative or hydrolytic. Oxidative deamination removes the amino group with the transfer of electrons, yielding an α-keto acid and NH3. A well-known example is the oxidative deamination of glutamate to α-ketoglutarate by glutamate dehydrogenase, using NAD+ or NADP+ as electron acceptors. Hydrolytic deamination uses deaminase enzymes to remove the amino group via hydrolysis, producing a keto or aldehyde and ammonia. These pathways enable cells to extract energy and to recycle nitrogen.

Deamination also occurs in nucleic acids. Spontaneous or enzyme-catalyzed deamination of cytosine to uracil, or of adenine to hypoxanthine, can introduce mutations during replication if unrepaired. Enzymes such as cytidine deaminases and the AID/APOBEC family mediate cytosine deamination for RNA editing and, in the immune system, antibody diversification.

Overall, deaminating is a central concept in metabolism and molecular biology, affecting nitrogen balance, metabolism of carbon skeletons, mutation rates, and regulatory processes used in physiology and immunity.