From The School of Biomedical Sciences Wiki
Deamination is the process that removes an Amine group from a molecule.
Deamination of Nucleotide Bases:
- Removing an amine group from a base can alter its structure.
- Deamination of Cytosine transforms it into Uracil
- Uracil Deamination of Adenine transforms it into Hypoxanthine
- Hypoxanthine Deamination of Guanine transforms it into Thymine 
- Deamination of Amino Acids:
The organic acid containing an oxygen with a double bond is usually respired.
- ↑ http://www.bath.ac.uk/bio-sci/oer/DNA%20damage%20deamination.htm
- ↑ Boyle M. (2008) Biology, 3rd edition, London: Collins. p242