5-bromouracil
|
|
5-bromouracil (or 5-Bromo-2,4(1H,3H)-pyrimidinedione or 5-BrU or 5-BU) is a component of 5-bromo-2-deoxy-uridine.
5-BrU a brominated derivative of uracil that acts as an antimetabolite or base analog, substituting for thymine in DNA and can induce DNA mutation in the same way as 2-Aminopurine. It is used mainly as an experimental mutagen, but its deoxyriboside derivitive (5-bromo-2-deoxy-uridine) is used to treat neoplasms.
5-BrU exists in two forms (tautomers) which both have different base pairing properties. The keto form (pictured) is complementary to adenine so this can be incorporated into DNA by aligning opposite adenine residues during DNA replication. Alternatively, the enol (or ion) form is complementary to guanine. This means that 5-BrU can be present in DNA either opposite adenine or guanine.
The two forms frequently interchange so base-pairing properties can become altered at any time. The result of this is that during a subsequent round of replication a different base is aligned opposite the 5-BrU residue. Further rounds of replication 'fix' the change by incorporating a normal nitrogen base into the complementary strand.
Thus 5-BrU induces a point mutation via base substitution. This base pair will change from a T-A to a G-C after a number of replication cycles.
Missing image
Bromouracil.jpg
Image:bromouracil.jpg
Characteristics
Molecular formula: C4H3BrN2O2 Molecular weight: 191.0 CAS number: 51-20-7
References
- Griffiths, Anthony J. et al (2005). Introduction to Genetic Analysis (8th Ed.). W.H. Freeman. ISBN 0-7167-4939-4