The Nucleic Acid Modification Database

Adenine substituted with a methyl group at position N-1.

A methyladenine that is adenine substituted with a methyl group at position N-3.

A methyladenine in which the methyl substituent is located at position 4.

A methyladenine that is 9H-purin-6-amine substituted by a methyl group at the amino nitrogen.

Adenine substituted with a methyl group at position N-7.

Adenine substituted with a methyl group at position N-9.

A 6-alkylaminopurine that is adenine where one of the hydrogens of the amino group is replaced by a hydroxymethyl group.

A member of the class of 6-aminopurinnes that is adenine in which one of the exocyclic amino hydrogens is replaced by a hydroxy group.

A member of the class of 2,6-diaminopurines that is 9H-purine in which the hydrogens at positions 2 and 6 are replaced by amino groups.

A 2,6-diaminopurine that is the N(6)-hydroxy derivative of 2,6-diamino-3H-purine.

A tertiary amine that is adenine substituted at N-6 by geminal methyl groups.

A nucleobase analogue that is adenine in which one of the exocyclic amino hydrogens is replaced by a carbamoylmethyl group.

Guanosine substituted with a methyl group at position N-1

A methylguanine in which the methyl group is located at the N2-position.

A methylguanine carrying the methyl substituent at position 3.

A methylguanine in which the methyl group is positioned on the oxygen at position 6.

A methylguanine that is guanine substituted by a methyl group at position 7.

An oxopurine that is guanine which is substituted by an oxo group at position 8.

A 7-deazaguanosine ribonucleoside that has 7-carbamoyl-7-deazaguanine as the nucleobase.

A nucleobase analogue obtained by addition of an etheno group across positions 1 and N2 of guanine.

A nucleobase analogue obtained by addition of an etheno group across positions N2 and 3 of guanine.

A guanosine where the hydrogens of the amine group at C-2 are substituted by methyl groups.

An alanine derivative consisting of alanine having a 6-oxo-6,9-dihydro-1H-purin-2-yl group attached to the amino function.

A pyrimidone that is cytosine in which the hydrogen attached to the nitrogen at position 1 is substituted by a methyl group.

Pyrimidine substituted with a methoxy group at position C-2 and an amine group at C-4.

A pyrimidone that is cytosine substituted by an ethyl group at position 3.

A pyrimidone that is cytosine in which the hydrogen attached to the nitrogen at position 3 is substituted by a methyl group.

A pyrimidone that is cytosine bearing an N(4)-methyl substituent.

A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a carboxy group.

A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a formyl group.

A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a hydroxymethyl group.

A beta-D-glucoside derived from formal condensation of the hydroxy group of 5-(hydroxymethyl)cytosine with the anomeric hydroxy group of D-glucopyranose.

A pyrimidine that is a derivative of cytosine, having a methyl group at the 5-position.

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

A purine 2'-deoxyribonucleoside that is inosine in which the hydroxy group at position 2' is replaced by a hydrogen

ID	Symbol	Common_Name	Chemical_Formula	Nucleoside_Mass	Description
1	1mA	1-methyladenine	C6H7N5	149.16	Adenine substituted with a methyl group at position N-1.
2	3mA	3-methyladenine	C6H7N5	149.16	A methyladenine that is adenine substituted with a methyl group at position N-3.
3	4mA	4-methyladenine	C6H9N5	151.17	A methyladenine in which the methyl substituent is located at position 4.
4	6mA	6-methyladenine	C6H7N5	149.16	A methyladenine that is 9H-purin-6-amine substituted by a methyl group at the amino nitrogen.
5	7mA	7-methyladenine	C6H7N5	149.16	Adenine substituted with a methyl group at position N-7.
6	9mA	9-methyladenine	C6H7N5	149.16	Adenine substituted with a methyl group at position N-9.
7	6hmA	6-hydroxymethyladenine	C6H7N5O	165.16	A 6-alkylaminopurine that is adenine where one of the hydrogens of the amino group is replaced by a hydroxymethyl group.
8	HAP	6-hydroxyaminopurine	C5H5N5O	151.13	A member of the class of 6-aminopurinnes that is adenine in which one of the exocyclic amino hydrogens is replaced by a hydroxy group.
9	m2A	2-aminoadenine	C5H6N6	150.15	A member of the class of 2,6-diaminopurines that is 9H-purine in which the hydrogens at positions 2 and 6 are replaced by amino groups.
10	AHAP	2-amino-6-hydroxyaminopurine	C5H6N6O	166.14	A 2,6-diaminopurine that is the N(6)-hydroxy derivative of 2,6-diamino-3H-purine.
11	6-DMA	N6,N6-dimethyladenine	C7H9N5	163.18	A tertiary amine that is adenine substituted at N-6 by geminal methyl groups.
12	ncm6A	N6-carbamoylmethyladenine	C7H8N6O	192.18	A nucleobase analogue that is adenine in which one of the exocyclic amino hydrogens is replaced by a carbamoylmethyl group.
13	ɛA	1,N6-ethenoadenine	C7H6N5+	160.16
14	1mG	1-methylguanine	C6H7N5O	165.16	Guanosine substituted with a methyl group at position N-1
15	2mG	2-methylguanine	C6H7N5O	165.16	A methylguanine in which the methyl group is located at the N2-position.
16	3mG	3-methylguanine	C6H7N5O	165.16	A methylguanine carrying the methyl substituent at position 3.
17	m6G	6-O-methylguanine	C6H7N5O	165.16	A methylguanine in which the methyl group is positioned on the oxygen at position 6.
18	7mG	7-methylguanine	C6H7N5O	165.16	A methylguanine that is guanine substituted by a methyl group at position 7.
19	8-oxo-G	8-oxoguanine	C5H3N5O2	165.11	An oxopurine that is guanine which is substituted by an oxo group at position 8.
20	ADG	7-amido-7-deazaguanosine	C12H15N5O6	325.28	A 7-deazaguanosine ribonucleoside that has 7-carbamoyl-7-deazaguanine as the nucleobase.
21	1,N(2)-ɛG	1,N2-ethenoguanine	C7H5N5O	175.15	A nucleobase analogue obtained by addition of an etheno group across positions 1 and N2 of guanine.
22	N(2),3-ɛG	N2,3-ethenoguanine	C7H5N5O	175.15	A nucleobase analogue obtained by addition of an etheno group across positions N2 and 3 of guanine.
23	m22G	N2,N2-dimethylguanosine	C12H17N5O5	311.3	A guanosine where the hydrogens of the amine group at C-2 are substituted by methyl groups.
24	CEG	N2-carboxyethylguanine	C8H9N5O3	223.19	An alanine derivative consisting of alanine having a 6-oxo-6,9-dihydro-1H-purin-2-yl group attached to the amino function.
25	1mC	1-methylcytosine	C5H7N3O	125.13	A pyrimidone that is cytosine in which the hydrogen attached to the nitrogen at position 1 is substituted by a methyl group.
26	m2C	2-O-methylcytosine	C5H7N3O	125.13	Pyrimidine substituted with a methoxy group at position C-2 and an amine group at C-4.
27	e3C	3-ethylcytosine	C6H9N3O	139.16	A pyrimidone that is cytosine substituted by an ethyl group at position 3.
28	3mC	3-methylcytosine	C5H7N3O	125.13	A pyrimidone that is cytosine in which the hydrogen attached to the nitrogen at position 3 is substituted by a methyl group.
29	ɛC	3,N4-ethenocytosine	C6H5N3O	135.12
30	4mC	4-methylcytosine	C5H7N3O	125.13	A pyrimidone that is cytosine bearing an N(4)-methyl substituent.
31	5caC	5-carboxylcytosine	C5H5N3O3	155.11	A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a carboxy group.
32	5fC	5-formylcytosine	C5H5N3O2	139.11	A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a formyl group.
33	5hmC	5-hydroxymethylcytosine	C5H7N3O2	141.13	A nucleobase analogue that is cytosine in which the hydrogen at position 5 is replaced by a hydroxymethyl group.
34	5gmC	5-glucosylmethylcytosine	C11H17N3O7	303.27	A beta-D-glucoside derived from formal condensation of the hydroxy group of 5-(hydroxymethyl)cytosine with the anomeric hydroxy group of D-glucopyranose.
35	5mC	5-methylcytosine	C5H7N3O	125.13	A pyrimidine that is a derivative of cytosine, having a methyl group at the 5-position.
36	putThy	α-putrescinylthymine	C9H16N4O2	212.25	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.
37	1mT	1,5-dimethyluracil	C6H8N2O2	140.14	A pyrimidone that is uracil with methyl group substituents at positions 1 and 5
38	3mT	3,5-dimethyluracil	C6H8N2O2	140.14	A pyrimidone that is uracil with methyl group substituents at positions 3 and 5
39	O4-meT	O(4)-methylthymine	C6H8N2O2	140.14	A methylthymine in which the methyl group is located at the O4-position
40	diHT	5,6-dihydrothymine	C5H8N2O2	128.13	A pyrimidone obtained by formal addition of hydrogen across the 5,6-position of thymine.
41	5hmU	5-hydroxymethyluracil	C5H6N2O3	142.11	A primary alcohol that is uracil bearing a hydroxymethyl substituent at the 5-position.
42	5fU	5-formyluracil	C5H4N2O3	140.1	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.
43	base J	(beta-D-glucopyranosyloxymethyl)deoxyuridine 5'-monophosphate	C16H25N2O14P	500.35	A pyrimidine 2'-deoxyribonucleoside 5'-monophosphate having beta-D-glucopyranosyloxymethyluracil (base J) as the nucleobase
44	dhpUra	5-(4,5-dihydroxypentyl)uracil	C9H14N2O4	214.22	A nucleobase analogue that is uracil substituted at position 5 by a 4,5-dihydroxypentyl group.
45	5caU	uracil-5-carboxylic acid	C5H4N2O4	156.1
46	5-NeOmdU	5-(2-aminoethoxy)methyl-2'-deoxyuridine	C12H19N3O6	301.3	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.
47	dU	2'-deoxyuridine	C9H12N2O5	228.2	A pyrimidine 2'-deoxyribonucleoside having uracil as the nucleobase
48	DHdU	5,6-dihydroxy-2'-deoxyuridine	C9H12N2O7	260.2	A pyrimidine 2'-deoxyribonucleoside having 5,6-dihydroxyuracil as the nucleobase
49	5-NedU	5-(2-aminoethyl)-2'-deoxyuridine	C11H17N3O5	271.27	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.
50	dhpdU	2'-deoxy-5-(4,5-dihydroxypentyl)uridine	C14H22N2O7	330.34	A pyrimidine 2'-deoxyribonucleoside having 5-(4,5-dihydroxypentyl)uracil as the nucleobase
51	dI	2'-deoxyinosine	C10H12N4O4	252.23	A purine 2'-deoxyribonucleoside that is inosine in which the hydroxy group at position 2' is replaced by a hydrogen