MolDraw › 3D molecule models › Guanine structure
Guanine structure and 3D model (C5H5N5O)
Guanine is a purine base with a C=O at C6 and an NH₂ group at C2. It pairs with cytosine in DNA and RNA.
Drag to rotate · pinch or scroll to zoom. 3D coordinates: computed with RDKit (ETKDG conformer, force-field optimised).
Guanine at a glance
| Formula | C5H5N5O |
|---|---|
| Molar mass | 151.13 g/mol |
| IUPAC name | 2-amino-1,7-dihydropurin-6-one |
| Atoms / bonds | 16 / 17 |
| H-bond donors / acceptors | 3 / 4 |
| logP (estimated) | -0.8 |
| SMILES | C1=NC2=C(N1)C(=O)NC(=N2)N |
| InChIKey | UYTPUPDQBNUYGX-UHFFFAOYSA-N |
| PubChem | 135398634 |
What the 3D model of Guanine shows
The model contains 16 atoms (11 heavy atoms and 5 hydrogens) joined by 17 bonds; in ball-and-stick mode every stick is one bond, and double or aromatic bonds are drawn as multiple sticks. Switch to space-filling to see the molecule as its electron cloud, scaled to van der Waals radii: this is the shape other molecules actually "feel". It can donate 3 and accept 4 hydrogen bonds, and its estimated logP of -0.8 means it is very water-loving (hydrophilic). Its topological polar surface area is 100 Ų.
Shape and bond angles
| Atom(s) | Geometry / hybridisation | Angles & lengths |
|---|---|---|
| ring atoms | Trigonal planar, sp²; fused rings | ≈ 108–128° |
| C6 carbonyl carbon | Trigonal planar, sp² | ≈ 120° |
| exocyclic NH₂ | Near-planar, conjugated | ≈ 120° |
Is Guanine polar?
Yes. It has several N–H donors and N and O acceptors. Its crystals are packed with hydrogen bonds, so it barely dissolves in water.
Elemental composition of C5H5N5O
| Element | Atoms | Mass (g/mol) | Mass % |
|---|---|---|---|
| Carbon (C) | 5 | 60.055 | 39.74% |
| Hydrogen (H) | 5 | 5.040 | 3.33% |
| Nitrogen (N) | 5 | 70.035 | 46.34% |
| Oxygen (O) | 1 | 15.999 | 10.59% |
Calculated from IUPAC standard atomic weights. Check any formula with the molar mass calculator.
Uses of guanine
- One of the four bases in DNA and RNA
- Part of GTP, which powers protein synthesis and cell signalling
- Guanine crystals give the shimmer in fish scales and some cosmetics
Interesting facts
- Guanine was first isolated from guano (bird droppings), which gave it its name.
- The G–C pair has three hydrogen bonds, one more than A–T.
- Crystalline guanine is used as a pearly pigment called pearl essence.
Drawing structures for your notes? MolDraw is a free online chemical structure editor for molecules, reactions and lab diagrams.
Open MolDraw editorFrequently asked questions
What is the structure of Guanine?
Guanine is a purine base with a C=O at C6 and an NH₂ group at C2. It pairs with cytosine in DNA and RNA. Its SMILES is C1=NC2=C(N1)C(=O)NC(=N2)N.
Why does guanine pair with cytosine?
Their shapes line up three hydrogen bonds: guanine's C=O, ring N–H and NH₂ match cytosine's NH₂, ring N and C=O.
Is guanine a purine?
Yes. Like adenine it has a six-membered ring fused to a five-membered ring.
What is the chemical formula and molar mass of Guanine?
Guanine is C5H5N5O with a molar mass of 151.13 g/mol. It contains 16 atoms: 5 carbon, 5 hydrogen, 5 nitrogen, 1 oxygen.
What is the IUPAC name of Guanine?
The IUPAC name is 2-amino-1,7-dihydropurin-6-one.
How do I draw Guanine?
Open the MolDraw editor, paste the SMILES C1=NC2=C(N1)C(=O)NC(=N2)N or type "Guanine" in name search, and the structure is drawn for you. You can then export it as PNG, SVG, MOL or CDXML.