nutrient
Histidine
An essential amino acid whose side chain can exchange protons.
Educational draft · Human scientific and editorial review pending. About review status
Histidine’s side chain can be uncharged or positively charged near physiological pH, which lets it participate in protein active sites.
How it works
A side chain that moves protons
Histidine can accept or donate a proton, helping some protein active sites carry out acid–base chemistry.
Related topics
Histidine is used to build Protein
Histidine is one of the amino acids used to assemble proteins.
Evidence: Established · Source checked 2026-09-05 · Sources: NIH National Library of Medicine: Biochemistry, Essential Amino Acids
Worth knowing
It is one of nine essential amino acids. Humans cannot synthesise histidine in sufficient amounts and obtain it from dietary protein.
A closer look
Its charge depends on its surroundings
Whether histidine accepts or donates a proton depends on the surrounding protein environment and local pH.
References
Source-checked local draft.
Human editorial review pending.
- NIH National Library of Medicine (opens in new tab)Biochemistry, Essential Amino AcidsChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Protein CatabolismChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Primary Protein StructureChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Collagen SynthesisChecked 2026-09-05
Take it into the kitchen
Explore this nutrient in simple meals. Recipe pages show estimated amounts and missing data.
Chicken corn tortilla fold · 20 min →
Pineapple cashew chicken pan · 25 min →
Coconut ginger chicken rice · 25 min →
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