HPLC
HPLC splits a sample into its parts and shows each one as a peak on a chart. The bigger the main peak, the higher the purity, shown as a percentage.
The Nautic Peptide Library
Everything about peptides, in plain English.
What peptides are, how they are made and tested, and the scientists behind the biggest discoveries. No jargon, just the interesting parts.
01 The basics
What is a peptide?
A peptide is a short chain of amino acids. Amino acids are the same building blocks that make up every protein in your body. Each link in the chain is called a peptide bond, and every time two amino acids join, they give off a tiny drop of water.
There are 20 main amino acids, and each has a one-letter code. G is glycine, H is histidine and K is lysine, so the peptide GHK is simply those three amino acids in a row.
2–50amino acids long is a typical peptide. Longer chains are called proteins.
20main amino acids. Mixed in different orders, they make almost endless peptides.
18.02is the weight of the water given off each time two amino acids join (in g/mol).
02 Try it
Peptide chain builder
Type some amino-acid letters, or tap a famous example. The builder draws the chain and works out how much it weighs.
Letters: A C D E F G H I K L M N P Q R S T V W Y
- Length
- 3
- Molecular weight
- 340.4
- Peptide bonds
- 2
Weight is in g/mol and assumes a simple straight chain. Some real peptides have small extras attached, so their true weight is a little different.
03 Discoveries
The discoveries that built peptide science
The first peptide hormone made in a lab
Vincent du Vigneaud showed that oxytocin is just nine amino acids long, then made it from scratch. It was the first peptide hormone ever made in a lab, and it won him the 1955 Nobel Prize in Chemistry.
An enzyme built one link at a time
Using his bead method, Merrifield's lab built a whole enzyme, ribonuclease A, by adding its 124 amino acids one by one. He also made melittin, a peptide from bee venom.
A three-amino-acid peptide in human blood
Loren Pickart discovered GHK in human blood. It is only three amino acids long, and it naturally grabs onto copper, which is where the name GHK-Cu comes from.
Thymosin α1 is sequenced
Allan Goldstein's team mapped a 28-amino-acid peptide taken from the thymus gland of calves. The extract it came from turned out to contain 30 to 40 different peptides.
A Nobel Prize for solid-phase synthesis
Merrifield won the Nobel Prize in Chemistry. The committee explained why accuracy matters: raising each step's success rate to 99.5% lifted the finished yield of a long peptide from 0.003% to 61%.
A peptide coded inside mitochondria
Scientists including Changhan Lee and Pinchas Cohen found MOTS-c, a 16-amino-acid peptide whose instructions sit in the DNA of mitochondria, the cell's power stations. Mitochondrial DNA was known to code for only 13 proteins, so finding a new peptide there was a surprise.
04 Making & testing
How peptides are made
- AnchorThe first amino acid is attached to a tiny resin bead.
- CoupleThe next amino acid is added, forming a new peptide bond.
- WashLeftover chemicals are rinsed away while the chain stays on the bead.
- RepeatCouple and wash again, one amino acid at a time, until the sequence is complete.
- Release & purifyThe finished chain is cut free, purified (usually by HPLC) and freeze-dried into a powder.
How quality is measured
Mass spectrometry
This test weighs the molecule. If the weight matches what the sequence should weigh, it confirms the peptide's identity.
Certificate of analysis
A COA is one page that lists a batch's test results: purity, identity, batch number and test date.
Why peptides arrive as powder
Peptides are freeze-dried (lyophilised), which removes the water and leaves a white powder in a sealed vial. In powder form they last much longer. Labs usually store them cold, dry and out of the light.
05 Australia
How peptides are regulated in Australia
In Australia, peptides used as medicines are overseen by the Therapeutic Goods Administration (TGA). Peptide medicines such as insulin are checked for quality, safety and effectiveness before they can be sold, and many need a prescription.
Peptides in skincare, such as serums and creams, can count as cosmetics instead. Cosmetic labels must list every ingredient.
The TGA's own guides explain the rules in detail:
06 Glossary
Peptide glossary
- Amino acid
- One of the small building blocks that link together to make peptides and proteins.
- Peptide bond
- The link between two amino acids, formed when they join and release water.
- Residue
- An amino acid once it is part of a chain.
- Sequence
- The order of the amino acids in a chain, read from start to finish.
- N-terminus / C-terminus
- The start and the end of a peptide chain.
- Molecular weight
- How much a molecule weighs, measured in g/mol or daltons.
- Solid-phase synthesis
- Building a peptide on a resin bead, one amino acid at a time.
- Lyophilisation
- Freeze-drying: removing water to leave a long-lasting powder.
- HPLC
- The standard test for how pure a peptide is.
- Mass spectrometry
- A technique that measures a molecule's mass to confirm its identity.
- COA
- Certificate of analysis: a batch's test results on one page.
- Acetylation / amidation
- Small chemical caps added to the start or end of a chain.