---
title: "Histidine: research glossary | Sable Peptides"
description: "Histidine (three-letter code His, one-letter code H) is an amino acid with an imidazole side chain whose pKa near 6 allows it to be either neutral or posit"
canonical: https://www.sablepeptides.co.uk/glossary/histidine
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

Glossary

# Histidine

Histidine (three-letter code His, one-letter code H) is an amino acid with an imidazole side chain whose pKa near 6 allows it to be either neutral or positively charged under laboratory conditions. Histidine binds metal ions, such as copper in GHK-Cu, and is particularly prone to racemisation during coupling.

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

## Related terms

-   [Amino acid](/glossary/amino-acid)
-   [Racemisation](/glossary/racemisation)
-   [One-letter code](/glossary/one-letter-code)

## Reference data

-   [Ghk-Cu](/ref/ghk-cu)

## Related products

-   [https://www.sablepeptides.co.uk/product/ghk-cu-50mg](https://www.sablepeptides.co.uk/product/ghk-cu-50mg)

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