---
title: "Tryptophan Structure (C11H12N2O2): 3D Model, Formula & Molar Mass | MolDraw"
url: https://www.moldraw.com/molecules/tryptophan.html
description: "Structure of Tryptophan (C11H12N2O2, 204.23 g/mol): rotatable 3D model, 2D skeletal formula, IUPAC name, SMILES, shape, polarity, uses and FAQ."
lang: en
publisher: Scidart Academy
generated: 2026-10-26
---
[MolDraw](https://www.moldraw.com/) › [3D molecule models](https://www.moldraw.com/molecules/) › Tryptophan structure

# Tryptophan structure and 3D model (C11H12N2O2)

L-tryptophan is an amino acid whose side chain is an indole ring: a benzene ring fused to a pyrrole. It is the largest of the 20 standard amino acids.

**Quick answer:** Tryptophan is **C11H12N2O2**, molar mass **204.23 g/mol**. Flat indole ring on a tetrahedral amino acid core; forms a zwitterion and is sparingly soluble in water.

Atom labels Hydrogens Spin

Drag to rotate · pinch or scroll to zoom. 3D coordinates: computed with RDKit (ETKDG conformer, force-field optimised).

## Tryptophan at a glance

| Formula | C11H12N2O2 |
| --- | --- |
| Molar mass | 204.23 g/mol |
| IUPAC name | (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid |
| Atoms / bonds | 27 / 28 |
| H-bond donors / acceptors | 3 / 2 |
| logP (estimated) | 1.1 |
| SMILES | `C1=CC=C2C(=C1)C(=CN2)C[C@@H](C(=O)O)N` |
| InChIKey | `QIVBCDIJIAJPQS-VIFPVBQESA-N` |
| PubChem | [6305](https://pubchem.ncbi.nlm.nih.gov/compound/6305) |

![2D structural formula of Tryptophan (C11H12N2O2)](https://www.moldraw.com/molecules/img/tryptophan.svg)

2D structure (skeletal formula) · [Draw it in MolDraw](https://www.moldraw.com/)

## What the 3D model of Tryptophan shows

The model contains **27 atoms** (15 heavy atoms and 12 hydrogens) joined by **28 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 2 hydrogen bonds, and its estimated logP of 1.1 means it is fairly balanced between water and fat. Its topological polar surface area is 79 Ų.

## Shape and bond angles

| Atom(s) | Geometry / hybridisation | Angles & lengths |
| --- | --- | --- |
| indole ring atoms | Trigonal planar, sp²; aromatic | ≈ 108–120° |
| α-carbon | Tetrahedral, sp³; stereocentre (S) | ≈ 109.5° |
| carboxyl carbon | Trigonal planar, sp² | ≈ 120° |

### Is Tryptophan polar?

Partly. The amino and acid groups are charged in water (zwitterion), but the large indole ring is hydrophobic, so it is one of the less soluble amino acids.

## Elemental composition of C11H12N2O2

| Element | Atoms | Mass (g/mol) | Mass % |
| --- | --- | --- | --- |
| Carbon (C) | 11 | 132.121 | 64.69% |
| Hydrogen (H) | 12 | 12.096 | 5.92% |
| Nitrogen (N) | 2 | 28.014 | 13.72% |
| Oxygen (O) | 2 | 31.998 | 15.67% |

Calculated from IUPAC standard atomic weights. Check any formula with the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html).

## Uses of tryptophan

- Essential amino acid that must come from food
- Precursor of serotonin, melatonin and niacin
- Its fluorescence is used to study protein folding

## Interesting facts

- Tryptophan absorbs UV light at about 280 nm, which is why proteins can be measured at that wavelength.
- It is one of the least common amino acids in most proteins.
- The idea that turkey makes you sleepy because of tryptophan is mostly a myth; turkey has about as much as other meats.

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## Frequently asked questions

### What is the structure of Tryptophan?

L-tryptophan is an amino acid whose side chain is an indole ring: a benzene ring fused to a pyrrole. It is the largest of the 20 standard amino acids. Its SMILES is C1=CC=C2C(=C1)C(=CN2)C[C@@H](C(=O)O)N.

### Is tryptophan an essential amino acid?

Yes. Humans cannot make it, so it must come from protein in the diet.

### What does the L in L-tryptophan mean?

It is the natural mirror-image form found in proteins. By CIP rules its α-carbon is (S).

### What is the chemical formula and molar mass of Tryptophan?

Tryptophan is C11H12N2O2 with a molar mass of 204.23 g/mol. It contains 27 atoms: 11 carbon, 12 hydrogen, 2 nitrogen, 2 oxygen.

### What is the IUPAC name of Tryptophan?

The IUPAC name is (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid.

### How do I draw Tryptophan?

Open the MolDraw editor, paste the SMILES C1=CC=C2C(=C1)C(=CN2)C[C@@H](C(=O)O)N or type "Tryptophan" in name search, and the structure is drawn for you. You can then export it as PNG, SVG, MOL or CDXML.

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