Amino Acid Chemistry

Before we talk about how amino acids link together and fold up to form proteins, it's worthwile to review their chemical properties and discuss the consequences for protein structure and function.

Nature uses twenty different amino acids (for the most part) to make proteins. All the amino acids share the same linking portion to attach to their neighbors in a protein, but their side chains are different. These varied side chains give each amino acid a distinct chemical personality -- some are long and floppy, others are small and compact; some are charged, others are neutral; some are greasy and hydrophobic, others are polar and hydrophilic.

The greasy boys

Alanine (A) is...
Leucine (L) is...
Isoleucine (I) is...
Valine (V) is...

The little guy

Glycine (G) is...

The alcoholics

Serine (S) is...
Threonine (T) is...

The sulfur buddies

Cysteine (C) is...
Methionine (M) is...

The charged ones

Lysine (K) is...
Arginine (R) is...
Aspartate (D) is...
Glutamate (E) is...

The polar bears

Asparagine (N) is...
Glutamine (Q) is...

The aromatic rings

Histidine (H) is...
Tyrosine (Y) is...
Phenylalanine (F) is...
Tryptophan (W) is...

The weird one

Proline (P) is...