Amino Acid Structures and Names

List of amino acids
There are 20 amino acids found in the human body.

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Science
Science
By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on September 01, 2019

 These are the structures for the twenty natural amino acids, plus the general structure for an amino acid.

Amino Acid General Structure

This is the general structure of an amino acid.
Amino Acid This is the general structure of an amino acid. This also shows the ionization of an amino acid at pH = 7.4. Todd Helmenstine

Amino acids are comprised of a functional group R attached to an amine group (NH2) and a carboxyl group (COOH). The functional groups can rotate, so amino acids display chirality. The (L) and (D) forms have the same chemical formulas, but they react differently in chemical reactions.

Alanine

This is the chemical structure of alanine.
Amino Acid This is the chemical structure of alanine. Todd Helmenstine

The molecular formula for alanine is C3H7NO2.

Arginine Chemical Structure

This is the chemical structure of arginine.
Amino Acid This is the chemical structure of arginine. Todd Helmenstine

The molecular formula for arginine is C6H14N4O2.

Asparagine Chemical Structure

This is the chemical structure of asparagine.
Amino Acid This is the chemical structure of asparagine. Todd Helmenstine

The molecular formula for asparagine is C4H8N2O3.

Aspartic Acid

This is the chemical structure of aspartic acid.
Amino Acid This is the chemical structure of aspartic acid. Todd Helmenstine

The molecular formula for aspartic acid is C4H7NO4.

Cysteine

This is the chemical structure of cysteine.
Amino Acid This is the chemical structure of cysteine. Todd Helmenstine

 The molecular formula for cysteine is C3H7NO2S. 

L-Glutamic Acid Chemical Structure

This is the chemical structure of L-glutamic acid.
Amino Acid This is the chemical structure of L-glutamic acid. Todd Helmenstine

The molecular formula for L-glutamic acid is C5H9NO4.

L-Glutamine Chemical Structure

This is the chemical structure of L-glutamine.
Amino Acid This is the chemical structure of L-glutamine. Todd Helmenstine

The molecular formula for L-glutamine is C5H10N2O3.

Glycine Chemical Structure

This is the chemical structure of glycine.
Amino Acid This is the chemical structure of glycine. Todd Helmenstine

The molecular formula for glycine is C2H5NO2.

L-Histidine Chemical Structure

This is the chemical structure of L-histidine.
Amino Acid This is the chemical structure of L-histidine. Todd Helmenstine

The molecular formula for L-histidine (his) is C6H9N3O2.

Isoleucine Chemical Structure

This is the chemical structure of isoleucine.
Amino Acid This is the chemical structure of isoleucine. Todd Helmenstine

The molecular formula for isoleucine is C6H13NO2.

Leucine Chemical Structure

This is the chemical structure of leucine.
Amino Acid This is the chemical structure of leucine. Todd Helmenstine

The molecular formula for leucine (Leu) is C6H13NO2.

L-Lysine Chemical Structure

This is the chemical structure of L-lysine.
Amino Acid This is the chemical structure of L-lysine. Todd Helmenstine

The molecular formula for L-Lysine (lys) is C6H14N2O2.

Methionine Chemical Structure

This is the chemical structure of methionine.
Amino Acid This is the chemical structure of methionine. Todd Helmenstine

The molecular formula for methionine is C5H11NO2S.

Phenylalanine Chemical Structure

This is the chemical structure of phenylalanine.
Amino Acid This is the chemical structure of phenylalanine. Todd Helmenstine

The molecular formula for phenylalanine is C9H11NO2.

Proline Chemical Structure

This is the chemical structure of proline.
Amino Acid This is the chemical structure of proline. Todd Helmenstine

The molecular formula for proline is C5H9NO2.

Serine Chemical Structure

This is the chemical structure of serine.
Amino Acid This is the chemical structure of serine. Todd Helmenstine

The molecular formula for serine is C3H7NO3.

Threonine Chemical Structure

This is the chemical structure of threonine.
Amino Acid This is the chemical structure of threonine. Todd Helmenstine

The molecular formula for threonine is C4H9NO3.

Tryptophan Chemical Structure

This is the chemical structure of tryptophan.
Amino Acid This is the chemical structure of tryptophan. Todd Helmenstine

The molecular formula for tryptophan is C11H12N2O2.

Tryptophan Metabolism

Tryptophan Metabolism
Tryptophan Metabolism. wikipedia public domain

L-tryptophan can be metabolized into serotonin and melatonin as well as niacin.

Tyrosine Chemical Structure

This is the chemical structure of tyrosine.
Amino Acid This is the chemical structure of tyrosine. Todd Helmenstine

The molecular formula for tyrosine is C9H11NO3.

Valine Chemical Structure

This is the chemical structure of valine.
Amino Acid This is the chemical structure of valine. Todd Helmenstine

The molecular formula for valine is C5H11NO2.

D-Glutamine Chemical Structure

This is the chemical structure of D-glutamine.
Amino Acid This is the chemical structure of D-glutamine. Todd Helmenstine

The molecular formula for D-glutamine is C5H10N2O3.

D-Gluconic Acid Chemical Structure

This is the chemical structure of D-gluconic acid.
Amino Acid This is the chemical structure of D-gluconic acid. NEUROtiker/PD

The molecular formula for D-gluconic acid is C6H12O7.

D-Glutamic Acid Chemical Structure

This is the chemical structure of D-glutamic acid.
This is the chemical structure of D-glutamic acid. Todd Helmenstine

The molecular formula for D-glutamic acid is C5H9NO4.

D-Histidine Chemical Structure

This is the chemical structure of the amino acid D-histidine.
Amino Acid This is the chemical structure of the amino acid D-histidine. Todd Helmenstine

The molecular formula for D-histidine is C6H9N3O2.

D-Isoleucine Chemical Structure

This is the chemical structure of D-isoleucine.
This is the chemical structure of D-isoleucine. Todd Helmenstine

The molecular formula for D-isoleucine is C6H13NO2.

L-Isoleucine Chemical Structure

This is the chemical structure of L-isoleucine.
This is the chemical structure of L-isoleucine. Todd Helmenstine

The molecular formula for L-isoleucine is C6H13NO2.

D-leucine Chemical Structure

This is the chemical structure of D-leucine.
Amino Acid This is the chemical structure of D-leucine. Todd Helmenstine

The molecular formula for D-leucine is C6H13NO2.

L-leucine Chemical Structure

This is the chemical structure of L-leucine.
Amino Acid This is the chemical structure of L-leucine. Todd Helmenstine

The molecular formula for L-leucine is C6H13NO2.

D-Lysine Chemical Structure

This is the chemical structure of D-lysine.
Amino Acid This is the chemical structure of D-lysine. Todd Helmenstine

The molecular formula for D-lysine (D-lys) is C6H14N2O2.

L-Methionine Chemical Structure

This is the chemical structure of L-methionine.
Amino Acid This is the chemical structure of L-methionine. Todd Helmenstine

The molecular formula for L-methionine is C5H11NO2S.

D-Methionine Chemical Structure

This is the chemical structure of D-methionine.
Amino Acid This is the chemical structure of D-methionine. Todd Helmenstine

The molecular formula for D-methionine is C5H11NO2S.

D-Norleucine or D-2-Aminohexanoic Acid Chemical Structure

This is the chemical structure of D-norleucine or D-2-aminohexanoic acid.
Amino Acid This is the chemical structure of D-norleucine or D-2-aminohexanoic acid. Todd Helmenstine

The molecular formula for D-norleucine or D-2-aminohexanoic acid is C6H13NO2.

Norleucine - 2-Aminohexanoic Acid Chemical Structure

This is the chemical structure of norleucine or 2-aminohexanoic acid.
Amino Acid This is the chemical structure of norleucine or 2-aminohexanoic acid. Todd Helmenstine

The molecular formula for norleucine or 2-aminohexanoic acid is C6H13NO2.

L-Norleucine or L-2-Aminohexanoic Acid Chemical Structure

This is the chemical structure of L-norleucine or L-2-aminohexanoic acid.
Amino Acid This is the chemical structure of L-norleucine or L-2-aminohexanoic acid. Todd Helmenstine

The molecular formula for L-norleucine or L-2-aminohexanoic acid is C6H13NO2.

Ornithine Chemical Structure

This is the chemical structure of ornithine.
Amino Acid This is the chemical structure of ornithine. Todd Helmenstine

The molecular formula for ornithine is C5H12N2O2.

L-Ornithine Chemical Structure

This is the chemical structure of L-ornithine.
Amino Acid This is the chemical structure of L-ornithine. Todd Helmenstine

The molecular formula for L-ornithine is C5H12N2O2.

D-Ornithine Chemical Structure

This is the chemical structure of D-ornithine.
Amino Acid This is the chemical structure of D-ornithine. Todd Helmenstine

The molecular formula for D-ornithine is C5H12N2O2.

L-Phenylalanine Chemical Structure

This is the chemical structure of L-phenylalanine.
Amino Acid This is the chemical structure of L-phenylalanine. Todd Helmenstine

The molecular formula for L-phenylalanine is C9H11NO2.

D-Phenylalanine Chemical Structure

This is the chemical structure of D-phenylalanine.
This is the chemical structure of D-phenylalanine. Todd Helmenstine

The molecular formula for D-phenylalanine is C9H11NO2.

D-Proline Chemical Structure

This is the chemical structure of D-proline.
Amino Acid This is the chemical structure of D-proline. Todd Helmenstine

The molecular formula for D-proline is C5H9NO2.

L-Proline Chemical Structure

This is the chemical structure of L-proline.
Amino Acid This is the chemical structure of L-proline. Todd Helmenstine

The molecular formula for L-proline is C5H9NO2.

L-Serine Chemical Structure

This is the chemical structure of L-serine.
Amino Acid This is the chemical structure of L-serine. Todd Helmenstine

The molecular formula for L-serine is C3H7NO3.

D-Serine Chemical Structure

This is the chemical structure of D-serine.
Amino Acid This is the chemical structure of D-serine. Todd Helmenstine

The molecular formula for D-serine is C3H7NO3.

D-Threonine Chemical Structure

This is the chemical structure of D-threonine.
Amino Acid This is the chemical structure of D-threonine. Todd Helmenstine

The molecular formula for D-threonine is C4H9NO3.

L-Threonine Chemical Structure

This is the chemical structure of L-threonine.
This is the chemical structure of L-threonine. Todd Helmenstine

The molecular formula for L-threonine is C4H9NO3.

L-Tyrosine Chemical Structure

This is the chemical structure of L-tyrosine.
Amino Acid This is the chemical structure of L-tyrosine. Todd Helmenstine

The molecular formula for L-tyrosine is C9H11NO3.

D-Tyrosine Chemical Structure

This is the chemical structure of D-tyrosine.
Amino Acid This is the chemical structure of D-tyrosine. Todd Helmenstine

The molecular formula for D-tyrosine is C9H11NO3.

D-Valine Chemical Structure

This is the chemical structure of D-valine.
Amino Acid This is the chemical structure of D-valine. Todd Helmenstine

The molecular formula for D-valine is C5H11NO2.

L-Valine Chemical Structure

This is the chemical structure of L-valine.
Amino Acid This is the chemical structure of L-valine. Todd Helmenstine

The molecular formula for L-valine is C5H11NO2.

D-Asparagine Chemical Structure

This is the chemical structure of D-asparagine.
Amino Acid This is the chemical structure of D-asparagine. Todd Helmenstine

The molecular formula for D-asparagine is C4H8N2O3.

L-Asparagine Chemical Structure

This is the chemical structure of L-asparagine.
Amino Acid This is the chemical structure of L-asparagine. Todd Helmenstine

The molecular formula for L-asparagine is C4H8N2O3.

D-Arginine Chemical Structure

This is the chemical structure of D-arginine.
Amino Acid This is the chemical structure of D-arginine. Todd Helmenstine

The molecular formula for D-arginine is C6H14N4O2.

L-Arginine Chemical Structure

This is the chemical structure of L-arginine.
Amino Acid This is the chemical structure of L-arginine. Todd Helmenstine

The molecular formula for L-arginine is C6H14N4O2.

Lysine Chemical Structure

This is the chemical structure of lysine.
This is the chemical structure of lysine. Todd Helmenstine

The molecular formula for lysine is C6H14N2O2.

D-Tryptophan Chemical Structure

This is the chemical structure of D-tryptophan.
Amino Acid This is the chemical structure of D-tryptophan. Todd Helmenstine

The molecular formula for D-tryptophan is C11H12N2O2.

L-Tryptophan Chemical Structure

This is the chemical structure of D-tryptophan.
Amino Acid This is the chemical structure of D-tryptophan. Todd Helmenstine

The molecular formula for L-tryptophan is C11H12N2O2.

D-Cysteine Chemical Structure

This is the chemical structure of D-cysteine.
Amino Acid This is the chemical structure of D-cysteine. Todd Helmenstine

The molecular formula for D-cysteine is C3H7NO2S.

L-cysteine Chemical Structure

This is the chemical structure of L-cysteine.
Amino Acid This is the chemical structure of L-cysteine. Todd Helmenstine

The molecular formula for L-cysteine is C3H7NO2S.

Histidine Chemical Structure

This is the chemical structure of histidine.
Amino Acid This is the chemical structure of histidine. Todd Helmenstine

The molecular formula for histidine (his) is C6H9N3O2.

Glutamine Chemical Structure

This is the chemical structure of glutamine.
Amino Acid This is the chemical structure of glutamine. Todd Helmenstine

The molecular formula for glutamine is C5H10N2O3.

Glutamic Acid Chemical Structure

This is the chemical structure of glutamic acid.
Amino Acid This is the chemical structure of glutamic acid. Todd Helmenstine

The molecular formula for glutamic acid is C5H9NO4.

L-Aspartic Acid Chemical Structure

This is the chemical structure of L-aspartic acid.
Amino Acid This is the chemical structure of L-aspartic acid. Todd Helmenstine

The molecular formula for aspartic acid is C4H7NO4.

D-Aspartic Acid Chemical Structure

This is the chemical structure of D-aspartic acid.
Amino Acid This is the chemical structure of D-aspartic acid. Todd Helmenstine

The molecular formula for aspartic acid is C4H7NO4.

Tryptophan

This is the chemical structure of tryptophan.
Amino Acid This is the chemical structure of tryptophan. Todd Helmenstine

 The molecular formula for tryptophan is C11H12N2O2

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Helmenstine, Anne Marie, Ph.D. "Amino Acid Structures and Names." ThoughtCo, Jul. 31, 2021, thoughtco.com/amino-acid-structures-4054180. Helmenstine, Anne Marie, Ph.D. (2021, July 31). Amino Acid Structures and Names. Retrieved from https://www.thoughtco.com/amino-acid-structures-4054180 Helmenstine, Anne Marie, Ph.D. "Amino Acid Structures and Names." ThoughtCo. https://www.thoughtco.com/amino-acid-structures-4054180 (accessed April 5, 2025).