UNG
Description
Product Specs
Product Science Overview
Uracil can be incorporated into DNA through two main processes:
- Deamination of Cytosine: Cytosine can spontaneously deaminate to form uracil, resulting in mutagenic U:G mispairs.
- Misincorporation of dUMP: During DNA replication, DNA polymerase can mistakenly incorporate dUMP instead of dTMP, leading to U:A pairs .
UDG plays a vital role in maintaining genomic integrity by excising uracil residues from DNA. This prevents the propagation of mutations during DNA replication and transcription. Without UDG, the presence of uracil in DNA could lead to mutations, potentially resulting in diseases such as cancer .
The mechanism of UDG involves several steps:
- Scanning and Binding: UDG scans the DNA for uracil residues by nonspecifically binding to the DNA strand and creating a kink in the backbone.
- Base Flipping: Once uracil is detected, UDG flips the uracil base out of the DNA helix into its active site.
- Cleavage: UDG cleaves the N-glycosidic bond between uracil and the deoxyribose sugar, creating an apyrimidinic (AP) site.
- Repair: The AP site is then recognized and processed by other enzymes in the BER pathway to restore the correct DNA sequence .
UDG is composed of a four-stranded parallel β-sheet surrounded by eight α-helices. The active site of UDG contains five highly conserved motifs that collectively catalyze the glycosidic bond cleavage :
- Water-activating loop: 63-QDPYH-67
- Proline-rich loop: 165-PPPPS-169
- Uracil-binding motif: 199-GVLLLN-204
- Glycine-Serine loop: 246-GS-247
- Minor groove intercalation loop: 268-HPSPLS-273
These motifs work together to ensure the high efficiency and specificity of UDG in repairing uracil-damaged DNA .
UDG is widely used in molecular biology, particularly in polymerase chain reaction (PCR) techniques. It helps prevent carryover contamination by degrading uracil-containing DNA from previous PCR amplifications. This ensures that only the target DNA is amplified, reducing the risk of false-positive results .
