Guanine

Guanine
Names
	Preferred IUPAC name 2-Amino-1,9-dihydro-6H-purin-6-one
	Other names 2-amino-6-hydroxypurine,; 2-aminohypoxanthine,; Guanine
Identifiers
CAS Number	73-40-5 ;
3D model (JSmol)	keto form: Interactive image; enol form: Interactive image;
Beilstein Reference	147911
ChEBI	CHEBI:16235 ;
ChEMBL	ChEMBL219568 ;
ChemSpider	744 ;
DrugBank	DB02377 ;
ECHA InfoCard	100.000.727
EC Number	200-799-8;
Gmelin Reference	431879
IUPHAR/BPS	4556;
KEGG	C00242 ;
PubChem CID	135398634;
RTECS number	MF8260000;
UNII	5Z93L87A1R ;
CompTox Dashboard (EPA)	DTXSID9052476 ;
	InChI InChI=1S/C5H5N5O/c6-5-9-3-2(4(11)10-5)7-1-8-3/h1H,(H4,6,7,8,9,10,11) Key: UYTPUPDQBNUYGX-UHFFFAOYSA-N ; InChI=1/C5H5N5O/c6-5-9-3-2(4(11)10-5)7-1-8-3/h1H,(H4,6,7,8,9,10,11) Key: UYTPUPDQBNUYGX-UHFFFAOYAE;
	SMILES keto form: N1C(N)=NC=2NC=NC2C1=O; enol form: OC1=C2N=CNC2=NC(=N1)N;
Properties
Chemical formula	C5H5N5O
Molar mass	151.13 g/mol
Appearance	White amorphous solid.
Density	2.200 g/cm3 (calculated)
Melting point	360 °C (680 °F; 633 K) decomposes
Boiling point	Sublimes
Solubility in water	Insoluble.
Acidity (pKa)	3.3 (amide), 9.2 (secondary), 12.3 (primary)
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Irritant
NFPA 704 (fire diamond)	1 1
Flash point	Non-flammable
Related compounds
Related compounds	Cytosine; Adenine; Thymine; Uracil
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Guanine (/ˈɡwɑːniːn/ ^ⓘ) (symbol G or Gua) is one of the four main nucleotide bases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is called guanosine.

With the formula C₅H₅N₅O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds. This unsaturated arrangement means the bicyclic molecule is planar.