What Is a Peptide? A Plain Guide
A short explainer on what peptides are, how they are described, and the terms you will see on a lab report.
Peptides appear often in research catalogues and on lab reports. This guide explains the basic terms in plain language.
What a peptide is
A peptide is a short chain of amino acids joined together. Longer chains are usually called proteins. There is no single sharp cut-off, but peptides are generally chains of up to a few dozen amino acids.
How peptides are described
Each peptide has a name and a sequence, which is the order of its amino acids. It also has a molecular weight, which is the figure that mass spectrometry checks on a lab report.
Why purity and identity matter
In research, the result you get depends on what is in the vial. Purity tells you how much of the material is the target compound. Identity tells you that the compound is the one on the label. A certificate of analysis reports both.
Terms you will see on a report
- HPLC: a method used to measure purity
- MS (mass spectrometry): a method used to confirm the molecular weight
- Batch or lot number: the identifier that links a vial to its results
- Lyophilized: freeze-dried into a powder for stability
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