An N-substituted putrescine that is thymine in which a hydrogen of the methyl group has been replaced by one of the amino groups of putrescine.

A pyrimidone that is uracil with methyl group substituents at positions 1 and 5

A pyrimidone that is uracil with methyl group substituents at positions 3 and 5

A methylthymine in which the methyl group is located at the O4-position

A pyrimidone obtained by formal addition of hydrogen across the 5,6-position of thymine.

A primary alcohol that is uracil bearing a hydroxymethyl substituent at the 5-position.

A pyrimidone resulting from the formal oxidation of the alcoholic hydroxy group of 5-hydroxymethyluracil to the corresponding aldehyde. It is a major one-electron photooxidation product of thymine in oligodeoxynucleotides.

A pyrimidine 2'-deoxyribonucleoside 5'-monophosphate having beta-D-glucopyranosyloxymethyluracil (base J) as the nucleobase

A nucleobase analogue that is uracil substituted at position 5 by a 4,5-dihydroxypentyl group.

A pyrimidine 2'-deoxyribonucleoside that is 5-hydroxymethyl-2'-deoxyuridine in which the hydroxymethyl group at position 5 has been formally converted to the corresponding 2-aminoethyl ether. It is a thymidine hypermodification replacing 40% of thymidine nucleotides in the Salmonellaphage ViI.

A pyrimidine 2'-deoxyribonucleoside having uracil as the nucleobase

A pyrimidine 2'-deoxyribonucleoside having 5,6-dihydroxyuracil as the nucleobase

A pyrimidine 2'-deoxyribonucleoside that is 2'-deoxyuridine in which the hydrogen at position 5 has been replaced by a 2-aminoethyl group. It is a thymidine hypermodification replacing 30% of thymidine in the DNA of the Pseudomonas phage M6.

A pyrimidine 2'-deoxyribonucleoside having 5-(4,5-dihydroxypentyl)uracil as the nucleobase