Deamination - Wikipedia
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 deaminates cytosine, but not 5-methylcytosine.
7.5: DNA Lesions - Biology LibreTexts
Dec 30, 2022 · Depurination of guanines (or adenines) is a common DNA lesion. Three of the four DNA bases, adenine, guanine, and cytosine, contain amine groups that can be lost in a variety of pH and temperature-dependent reactions that convert the bases to hypoxanthine, xanthine, and uracil, respectively.
The hydrolytic deamination of cytosine and 5-methylcytosine residues in DNA appears to contribute significantly to the appearance of spon-taneous mutations in microorganisms and in human disease. In the present work, we examined the mech anism of cytosine deamination and the response of the uncatalyzed reaction to changing tempera-ture.
Cytosine Deamination Plays a Primary Role in the Evolution of …
Sep 1, 2000 · Our results show that the deamination of 5-methylcytosine reduces the GC content of the human genome by ∼10%. Our results also indicate that the deamination of unmethylated cytosine is primarily responsible for the maintenance …
Base deamination is a major source of spontaneous mutagenesis in human cells, where cytosine (C), adenine (A), guanine (G), and 5-methyl cytosine (5mC) in DNA lose their exocyclic amine to become uracil (U), hypoxanthine, xanthine and thymine (T), respectively (Figure 1B).
Mutagenic consequences of cytosine alterations site-specifically ...
Sep 1, 2016 · The deamination of 5-methylcytosine and 5-bromocytosine rather than that of normal cytosine dramatically enhances the mutagenic potential in the human genome. Cytosine residues in CpG dinucleotides often undergo various types of modification, such as methylation, deamination, and halogenation.
The clock-like accumulation of germline and somatic mutations
Jun 17, 2024 · The process of spontaneous cytosine deamination contributes substantially to the mutation rate . The standard explanation is that because at methylated cytosines, the deamination rate results in a thymine, one of the canonical bases, the efficiency of repair is low [ 32 ].
Generation, Biological Consequences and Repair Mechanisms of Cytosine ...
Nov 6, 2008 · DNA glycosylases, the key enzyme in the base excision repair pathway, are highly conserved in evolution. Uracil constantly occurs in DNA. Uracil in DNA arises by spontaneous deamination of cytosine to generate pro-mutagenic U:G mispairs.
DNA methylation: past, present and future directions
Mar 1, 2000 · The increased mutability of 5-methylcytosine versus cytosine is thought to be influenced by three factors: differential repair efficiency, rate of spontaneous deamination, and rate of cell division. Deamination of cytosine forms uracil, which is readily recognized and repaired by the highly abundant and efficient uracil DNA glycosylase (UDG).
We show here that in bacteria which lack uracil-DNA glycosylase (Ung-) and cannot excise uracil residues from DNA, the rate of spontaneous transition at cytosine residues is raised to the...