In this section the main properties of the 20 different amino acids found in genetically encoded proteins will be outlined.
All amino acids have amino and carboxyl groups attached to the alpha-carbon atom.
Hence all amino acids in the protein are linked by peptide bonds. In each condensation reaction an -OH group is essentially lost from the participating carboxyl group and a hydrogen is lost from the amino group, ie water is eliminated. The three-dimensional structure and function of a protein are dependent on the sequence of amino acid side chains in the polypeptide. Amino acid side chains can be divided into several different classes based on their physico-chemical properties. The below diagram indicates the colour scheme for the atoms in this section.