Structures of Amino Acids

by Kamlesh Sahu

For all Tricks, It is necessary that you actually see these pictures in your mind.

We had kept Amino acids here according to the classification according to reactive group or R group

  1. Aliphatic - Glycine, Alanine, Valine, Leucine, Isoleucine

  2. Aromatic - Phenylalanine, Tyrosine, Tryptophan

  3. Hydroxy - Serine, Threonine

  4. Acidic - Aspartic Acid, Glutamic Acid

  5. Acid amide - Aspargine, Glutamine

  6. Basic - Arginine, Lysine, Histidine

  7. Sulphur - Cystine, Methionine

  8. Cyclic - Proline

Aliphatic  G A V L I


Glycine (G)

Alanine (A)

Valine (V)

Leucine (L)





Leucine (L)

Isoleucine (I)


See in every Amino acid number of carbon atom increases and remember the series G A V L I

Glycine is the simplest and does not show optical isomerisation due to absence of chiral carbon.

In Alanine one H of Glycine is replaced by CH3

Valine contain V in it

Leucine contain L see picture

Leucine is written two times in different arrangement

Leucine and Isoleucine are isomers, they have the same atomic weight, the methyl group is attached in different Carbon atom


Aromatic Phenylalanine (F), Tyrosine (Y), Tryptophan (W)


Phenylalanine (F)

Tryptophan (W)

Tyrosine (Y)


Tryptophan (W)

Tyrosine (Y)


Phenylalanine phenyl group is added in alanine so it becomes Phenylalanine

In Tryptophan W is written by using its cycle

Tyrosine contains 2 Y in it

Hydroxy - Serine (S), Threonine (T)


Serine (S)

Threonine (T)


for most of the Amino acid Alanine and Valine are precursor

some modification in these amino acids can change it into various amino acid

Serine is very similar to Alanine, here OH is added instead of H

Threonine is similar to Valine, hrere CH3 is replaced by OH


Acidic - Aspartic Acid, Glutamic Acid


Aspartic Acid (D)

Glutamic Acid (E)


Aspartic acid (D) also called as aspartate (when COOH of side chain is written COO-)

Glutamic acid (E) also called as glutamate


Acid amide - Aspargine (N), Glutamine (E)

Aspargine (N)

Glutamine (E)

Aspargine and Glutamine both are neutralized version of their respective acids

in both CONH2 is their instead of COOH

Basic - Arginine, Lysine, Histidine

Arginine (R)

Lysine (K)

Histidine (H)

Just practice many times


Sulphur containing- Cystine, Methionine

Cystine (C)

Methionine (M)



Cyclic - Proline

Proline (P)

Proline (P)

It is cyclic and Secondary amino acid some times called as Imino acid.

See P inside Proline

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