Histidine

Histidine

One of the 20 amino acids that make up proteins.

Chemistry

Keywords

histidine, His, amino acid, protein, peptide, polypeptide, polar side chain, zwitterionic structure, peptide bond, amide bond, amino acid sequence, molecule, organic chemistry, chemistry, biology, biochemistry

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Zwitterion

Histidine (C₆H₉N₃O₂)

Data

Molar mass: 155.15 g/mol

Melting point: 282 °C

Boiling point: 458 °C

Density: 1.423 g/cm³

Properties

Histidine is a semi-essential amino acid. It is a colourless, crystalline substance that is well soluble in water, weakly soluble in ethanol and insoluble in ether. It is an important constituent of haemoglobin. Decarboxylation of histidine results in histamine.

Occurrence and production

Histidine occurs in free form in plants, but it is abundant in bound form in proteins, such as casein, fibrin, keratin and the proteins found in egg whites. Histidine synthesis and breakdown are complex processes.

Uses

Histidine is a building block of proteins.

Zwitterion space-filling

Molecule

Molecule space-filling

Narration

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Amino acids

Amino acids are the monomers of proteins.

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