What is Histidine?

Histidine is an essential amino acid that plays a vital role in the biosynthesis of proteins. It comprises a carboxylic acid group, α-amino group, and an imidazole side chain thus labelling it into positively charged amino acid in terms of physiological pH.


Chemical Properties of Histidine 

Histidine is evident as it comprises the ring structure in its ‘R’ group consisting of 2 nitrogen.
Chemical Group: C6H9N3O2 
The abbreviation used to represent this essential amino acid is either ‘His’ or ‘H’.

Biochemistry  Imidazole chain is an element of catalytic sites found in certain enzymes and it is one of the most prevalent coordinating ligands in metalloproteins. In Order to activate it as a nucleophile in catalytic triads, basic nitrogen of histidine is used to abstract a proton from a cysteine, threonine, and serine. Whereas in the case of a proton shuttle, it is used to shuttle protons.

Aromaticity At each level of the ph-value, the imidazole ring of histidine is aromatic. It comprises of 6 pi electrons among which 2 form a nitrogen lone pair and four form 2 double bonds.  It can possibly lead to the formation of pi-stacking interactions but it is hard due to positive charges.

Benefits of Histidine 

  • L-Histidine is a vital amino acid that is needed by the body mainly in the growing stage of  children. Hence, it is present in means of supplementary or in food.
  • Various food products that include histidine are fish, meat and dairy products.
  • It is helpful in transferring a large amount of iron and copper.
  • It controls diarrhoea as it boosts absorption of calcium thus decreasing the histidine level. But excessive consumption would lead to some side effects such as constipation.
  • It has a symbolic mechanism in preventing internal bleeding and clotting of blood.

Frequently Asked Questions – FAQs


Define amino acids.

In simpler terms, Amino acids are organic compounds containing the basic amino groups (-NH2) and carboxyl groups (-COOH).

Give examples of essential amino acids.

Essential amino acids cannot be synthesized and hence must come from our diet. The 9 essential amino acids are – Isoleucine, histidine, lysine, leucine, phenylalanine, tryptophan, methionine, threonine, and valine.

What is the chemical formula of Histidine?

The chemical formula of Histidine C6H9N3O2.

Why are amino acids called amphoteric?

Amino acids have both acidic and basic properties. This is why they are amphoteric. The predominant form of the amino acid is based on the pH of the solution.

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