---
title: "b and y ions: research glossary | Sable Peptides"
description: "b and y ions are the main fragment types produced when a peptide backbone breaks at an amide bond during tandem mass spectrometry. b ions contain the N-ter"
canonical: https://www.sablepeptides.co.uk/glossary/b-and-y-ions
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

Glossary

# b and y ions

b and y ions are the main fragment types produced when a peptide backbone breaks at an amide bond during tandem mass spectrometry. b ions contain the N-terminus and y ions contain the C-terminus. Consecutive ions in a series differ by a residue mass, allowing sequence to be read.

Source: [en.wikipedia.org](https://en.wikipedia.org/wiki/Peptide_fragmentation)

## Related terms

-   [Peptide](/glossary/peptide)
-   [Residue](/glossary/residue)
-   [N-terminus](/glossary/n-terminus)
-   [C-terminus](/glossary/c-terminus)
-   [Sequence](/glossary/sequence)
-   [Mass spectrometry](/glossary/mass-spectrometry)
-   [Tandem mass spectrometry](/glossary/tandem-mass-spectrometry)

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