Cytosine-d2 is intended for use as an internal standard for the quantification of cytosine by GC- or LC-MS. Cytosine is a pyrimidine base.1 It forms complementary base pairs with the purine guanine in DNA and RNA and is a precursor of uracil . Methylation of cytosine is a key epigenetic mark that plays a role in gene regulation.2
1.Berg, J.M., Tymoczko, J.L., and Stryer, L.Nucleotide biosynthesisBiochemistry(2002) 2.Breiling, A., and Lyko, F.Epigenetic regulatory functions of DNA modifications: 5-methylcytosine and beyondEpigenetics Chromatin824(2015)