Science Basics
Natural vs. Synthetic Peptides: What’s the Difference?
A peptide found in nature can also be made in a laboratory. “Naturally occurring” describes where the molecule exists; “chemically synthesized” describes how a sample is made. Those labels can apply to the same peptide.
Peptide basics · Guide 4 of 4
What does naturally occurring mean?
It means the peptide exists in a living system. Plants, for example, produce signaling peptides involved in how their leaves develop. [1]
But finding a peptide in nature and taking a sample from nature are different things. A researcher could study material isolated from a living system or use a synthetic version of the same molecule.
What is a synthetic peptide?
Chemical peptide synthesis joins amino-acid building blocks to make a chosen chain. It can reproduce a naturally occurring structure or create an altered one. [2] [3]
“Synthetic” describes the production method. It does not, by itself, mean that the resulting molecule is new or different from one found in nature.
Can natural and synthetic peptides be identical?
They can have the same chemical structure. But the word “synthetic” alone does not establish a match. You need to know exactly which structure was made. [3]
The order of the building blocks—the sequence—is part of that description. Other details include their orientation and the chemical groups attached at the chain’s ends. Matching only a short name or sequence can leave out those differences. [4]
The distinction is between a molecule and a sample: two samples can contain the same target molecule without containing the same amounts of other substances.
Does either label tell you the purity?
No. Origin describes where something occurs or how it was made. Purity concerns the composition of a particular sample, which requires analytical evidence. Peptide analysis can combine methods that separate sample components with methods that examine their masses. Each contributes different information. [5]
A report’s sample identifier, method, and result matter more here than the words natural or synthetic. Neither origin nor a purity percentage alone establishes safety or suitability for personal use.
Learn what to check in a peptide paper’s methods and results →
Putting the labels together
Consider the illustrative description “a naturally occurring peptide, prepared by chemical synthesis.” It says the molecule occurs in nature and that this material was made chemically. It does not say the material was extracted from a plant or other organism.
To understand the rest, look separately at the stated chemical structure and the evidence about that sample. The origin label cannot answer every question about what is in the container.
References
- Lee et al. (2015): Competitive binding of antagonistic peptides fine-tunes stomatal patterning
- Merrifield (1963): Solid Phase Peptide Synthesis. I. The Synthesis of a Tetrapeptide
- Merrifield (1984): Solid Phase Synthesis — Nobel Lecture
- IUPAC-IUB: Nomenclature and Symbolism for Amino Acids and Peptides
- Waters: Mass-Directed Isolation of Synthetic Peptides Using the Waters SQ Detector 2