Deamination is a biological process that involves the removal of an amino group from a molecule. It is widespread across living organisms, serving various metabolic functions. It manages nitrogen compounds and plays a role in energy production.
The Deamination Process
An amino group is a functional group composed of a nitrogen atom bonded to two hydrogen atoms (-NH2). Deamination is the process that extracts this amino group from compounds, primarily amino acids, also from other nitrogen-containing molecules like nucleotides. This removal often results in the formation of ammonia and a corresponding keto acid.
Enzymes called deaminases catalyze these reactions. For instance, in oxidative deamination, the amino group is removed through an oxidation process. This mechanism is important in amino acid catabolism, converting excess amino acids into metabolic intermediates. Non-oxidative deamination also occurs, where the amino group is removed without oxidation.
Why Deamination Matters
Deamination is important for energy production. The remaining carbon skeletons from deaminated amino acids provide energy. These carbon skeletons can be converted into glucose or fats, or directly oxidized in metabolic cycles. This is relevant when carbohydrate levels are low, such as during fasting or starvation, allowing the body to use amino acids as an alternative energy source.
The process also plays a role in nitrogen balance and waste management. Deamination helps process excess amino acids, especially from high protein intake, managing nitrogen waste and preventing toxic ammonia buildup. Intermediates generated from deamination can also be utilized for the synthesis of other essential biological molecules, highlighting its dual role in catabolic and anabolic pathways.
What Happens After Deamination
After deamination, the amino group becomes ammonia (NH3). Ammonia is toxic to the body, especially the brain. To counteract this, the body converts ammonia into urea, a less toxic form, through the urea cycle.
This urea cycle takes place primarily in the liver, with steps in both mitochondria and cytosol. The urea formed in the liver is then transported through the bloodstream to the kidneys, where it is excreted in the urine. The remaining carbon skeleton or keto acid can enter various metabolic pathways. These keto acids can be used in the Krebs cycle for energy, or converted into glucose (through gluconeogenesis) or fatty acids for storage.