Tryptophan: The molecule that calms your mind
Tryptophan is an essential amino acid that is a parent molecule of Serotonin and Melatonin – molecules that regulate your sleep-wake cycle. Melatonin, in particular, is a hormone that plays a vital role in our body’s circadian rhythm (or body clock) which is important in regulating our body’s sleep-wake activities. Peak levels of melatonin are produced at nighttime. Serotonin, on the other hand, is important in regulating our mood. In fact, this molecule is involved in the treatment of depression. Without Tryptophan, Melatonin and Serotonin are not produced.
How does Tryptophan look like in Chemistry?

Let’s Get Building!
Using your Student Molecular Set from Duluth Labs let’s create the Tryptophan Molecule! You’ll need:
- 11 Carbon atoms
- 2 Oxygen atoms
- 12 Hydrogen atoms
- 2 Nitrogen atoms
- 12 Small connectors (compact small bonds for hydrogen)
- 11 Medium Connectors
- 10 Long connectors
- Molecular Tool (for Disassembly)
Put aside all the atoms and connectors needed.
Let’s Start Building With Our Amino Acid Skeleton portion!

Note: We will build the skeleton portion of our amino acid starting with our chiral carbon(α Carbon).
Steps:
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1
1. Get one carbon atom (α Carbon)then, place one hydrogen atom at the back side using one small connector.
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2
2. Then, get another carbon atom (β Carbon)then place this in front of α Carbon using 1 medium connector. Add 2 hydrogen atoms on β Carbon using 2 small connectors.
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3
3. Attach another carbon (Carbonyl Carbon) on α Carbon using 1 medium connector.
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4
4. Get an Oxygen atom and attach this to the Carbonyl Carbon using 2 long connectors.
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5
5. Get another Oxygen atom then attach this to the Carbonyl Carbon using a medium connector. Place a 1 hydrogen atom on this oxygen using one small connector.
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6
6. Then, get your Nitrogen atom and attach this to the α Carbon using one medium connector. Place 2 hydrogen atoms on this Nitrogen using 2 small connectors
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Yay! We've just built our amino acid skeleton!
Note: Let’s now attach the 5-membered ring of our indole portion at the beta (β) carbon! Let’s start with Carbon 3. We will build this portion in a clockwise direction.

Steps:
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1
1. Get one Carbon atom (Carbon 3)then attach this using 1 medium connector. Add 1 hydrogen atom to Carbon 3using 1 small connector.
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2
2. Attach another Carbon atom(Carbon 2)to Carbon 3 using 2 long connectors. Then, add 1 hydrogen atomto Carbon 2using 1 small connector.
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3
3. Get a nitrogen atom (Nitrogen 1) then attach this to Carbon 2 using a medium connector. Add 1 hydrogen atomto this nitrogen using 1 small connector.
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4
4. Attach a Carbon atom(Carbon 9) to Nitrogen 1 using 1 medium connector.
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5
5. Get another Carbon atom (Carbon 4) then attach this to Carbon 9using 2 long connectors.
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6
6. Join Carbon 3 and Carbon 4 together using a medium connector.
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Hooray! We now have our 5-membered portion!
Note: Let’s build the 6-membered ring of our indole portion starting with Carbon 5, in a counter clockwise direction.

Steps:
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1
1. Get one Carbon atom (Carbon 5) then attach this to Carbon 4 using 1 medium connector. Add 1 hydrogen atom to Carbon 5 using 1 small connector.
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2
2. Attach another Carbon atom (Carbon 6)to Carbon 5 using 2 long connectors. Then, add 1 hydrogen atom to Carbon 6 using 1 small connector.
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3
3. Get a Carbon atom (Carbon 7) then attach this to Carbon 6 using a medium connector. Add 1 hydrogen atom to Carbon 7 using 1 small connector.
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4
4. Attach another Carbon atom (Carbon 8) to Carbon 7 using 2 long connectors. Add 1 hydrogen atom to Carbon 8 using 1 small connector.
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5
5. Finally, join Carbon 8 and Carbon 9 together using a medium connector.
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6
Yay! We’ve just built our L-Tryptophan molecule.
Now, try this! Let’s build another L-Tryptophan molecule by following the steps outlined above. Then let’s try to interchange the Hydrogen attached to the alpha (α) carbon and the beta (β) Carbon containing the indole functional group.

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1
1. Build another tryptophan molecule following the steps outlined above.
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2
2. Detach the hydrogen atom and the beta (β) carbon containing the indole side chain.
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3
3. Place the hydrogen atom in front of the alpha (α) carbon.
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4
4. Then, attach the beta (β) carbon with the indole functional group at the back side of alpha (α) carbon.