Skip to main content
Science / Explained
SERIES: What Are PeptidesArticle 3 of 5
Twenty amino acids build every peptide the body makes

The body uses just 20 amino acids to build every peptide signal it runs. Think of these 20 amino acids as letters in an alphabet.

Link them in one sequence, you spell STOP. Use the identical letters in a different order, you spell POST. Same letters. Entirely different meanings.

This is how peptides work. Arrange 20 amino acids one way, and the body gets a hunger signal. Rearrange them, and the body gets a fullness signal.

The precision matters. Change the order enough to alter folding or receptor fit, and the signal can weaken, change, or disappear.

The body runs 7,000 distinct signals from just these 20 building blocks. Every peptide signal that regulates blood sugar, triggers appetite, dulls pain, or boosts immunity comes from rearranging the same 20 letters.

The building blocks are few. The variety they produce is vast.

OneMoreThing

A single amino acid substitution in the insulin gene causes a rare condition called MODY (Maturity-Onset Diabetes of the Young).One wrong letter in a 51-amino-acid sequence.The peptide folds incorrectly.The receptor does not recognize it.Blood sugar regulation fails.

The body spells insulin with a typo, and the signal breaks.This is why sequence matters at the atomic level.There is no room for error in a 20-letter alphabet writing life-or-death messages.

← Previous
Peptides work like one key in one lock
Next →
Peptides reach a wound before the immune system does
References2 sources

How to read these sources

This article uses primary sources and reviews to separate mechanism, human evidence, and context.

ReviewExpert synthesis
Show 4 more source types
Official LabelRegulator documents
Human TrialStudies in people
MechanismCell and pathway logic
Public UpdateNews or announcements
  1. Review

    Drug Discovery Today

    Elsevier

    Fosgerau, K., & Hoffmann, T. · 2015 Peptide therapeutics: current status and future directions. Read source

    Used Here For

    Supporting the point that peptides built from the same 20 amino acids can become targeted drugs.

    Good For

    Understanding peptide drug discovery trends and design tradeoffs.

    Not For

    Determining whether a specific product is approved, safe, or right for someone.

    Drug Discov Today 20(1):122-128
    PMID 25450771DOI 10.1016/j.drudis.2014.10.003
  2. Review

    Chemical Biology & Drug Design

    Wiley

    Craik, D.J., Fairlie, D.P., Liras, S., & Price, D. · 2013 The future of peptide-based drugs. Read source

    Used Here For

    Backing the idea that amino acid sequence and structure determine a peptide drug's function.

    Good For

    A broad view of how peptide structure informs drug design.

    Not For

    Clinical outcome data or treatment recommendations.

    Chem Biol Drug Des 81(1):136-147
    PMID 23253135DOI 10.1111/cbdd.12055