Everything about Deamination totally explained
Deamination is the removal of an
amine group from a
molecule.
In the
human body, deamination takes place in the
liver. Deamination is the process by which
amino acids are broken down. The amino group is removed from the amino acid and converted to
ammonia. The rest of the amino acid is made up of mostly
carbon and
hydrogen, and is recycled or oxidized for energy. Ammonia is toxic to the human system, and
enzymes convert it to
urea or
uric acid by addition of
carbon dioxide molecules (which isn't considered a deamination process) in the
urea cycle, which also takes place in the liver. Urea and uric acid can safely diffuse into the blood and then be excreted in urine.
Deamination reactions in DNA
Cytosine
Spontaneous deamination is the
hydrolysis reaction of
cytosine into
uracil, releasing
ammonia in the process. This can occur in vitro through the use of
bisulfite, which converts cytosine, but not
5-methylcytosine. This property has allowed researchers to
sequence methylated DNA to distinguish non-methylated cytosine (shown up as
uracil) and methylated cytosine (unaltered).
In
DNA, this spontaneous deamination is corrected for by the removal of uracil (product of cytosine deamination and
not part of DNA) and replacement with another cytosine.
5-methylcytosine
Spontaneous deamination of 5-methylcytosine results in
thymine and ammonia. In DNA, this reaction can't be corrected because the repair mechanisms don't recognize thymine as erroneous (as opposed to uracil), and, unless it affects the function of the
gene, the
mutation will persist. This flaw in the repair mechanism contributes to the rarity of
CpG sites in the
eukaryotic genome.
Additional Proteins Performing This Function
Further Information
Get more info on 'Deamination'.
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