---
title: "pKa: research glossary | Sable Peptides"
description: "The pKa is the negative logarithm of an acid dissociation constant and indicates the pH at which half of an ionisable group is protonated. Peptide side cha"
canonical: https://www.sablepeptides.co.uk/glossary/pka
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

Glossary

# pKa

The pKa is the negative logarithm of an acid dissociation constant and indicates the pH at which half of an ionisable group is protonated. Peptide side chains such as aspartate, glutamate, histidine, lysine and arginine each have characteristic pKa values, which together determine overall charge and isoelectric point.

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

## Related terms

-   [Peptide](/glossary/peptide)
-   [Isoelectric point](/glossary/isoelectric-point)
-   [Dissociation constant](/glossary/dissociation-constant)
-   [Lysine](/glossary/lysine)
-   [Arginine](/glossary/arginine)
-   [Histidine](/glossary/histidine)

[Back to glossary A–Z](/glossary/terms)

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