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en:sodium_bisulfite_reaction [2013/06/09 10:10] (current)
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 +======Sodium bisulfite reaction======
 +
 +**Sodium bisulfite**\\ {{pubchem>​small:​6399220}}
 +
 +Sodium bisulfite reaction transfers unmethylated cytosine to uracyl via sulphonation,​ hydrolytic deamination and alkali desulphonation. ​ Combination of this reaction and PCR can reveal which cytosine residues are methylated. ​ Therefore, this reaction is important in the epigenetics.
 +
 +
 +
 +=====Reaction=====
 +
 +====Cytosine + bisulfite====
 +
 +{{bio:​sodium_bisulfite.png|Sodium bisulfite reaction}}
 +
 +  -Reversible reaction of sulfonation of cytosine. Sulfonation reaction proceeds in low pH.
 +  -Hydrolytic deamination reaction converts sulfo-cytosine to sulfo-uracil.
 +  -Reversible reaction of desulfonation of sulfo-uracil by in the high pH conditions.
 +
 +
 +====5-Methylcytosine + bisulfite====
 +
 +{{bio:​sodium_bisulfite_meth.png|Sodium bisulfite reaction with methylated DNA}}
 +
 +
 +Although [[nucleobase#​5-methylcytosine]] can react with bisulfite, the reaction is extremely slow.
 +
 +
 +
 +====Examples====
 +|Unmethylated DNA|Partially methylated DNA|
 +|{{bio:​sodium_bisulfite_seq1.png|}}|{{bio:​sodium_bisulfite_seq2.png|}}|
 +|(upper row: substrate, lower row: product)||
 +
 +======References======
 +
 +  *{{pubmed>​long:​8065911}}
 +  *{{pubmed>​long:​8790415}}
 +
 +
 +{{tag>​methylation nucleotide chemical_modification}}