Explanation: Amino acids are different because they differ in the kind or the lateral chain ( R) that they have,
so the characteristics of these lateral chains have been used for classify them.
Very used classifications are the following:
Classification according to the side chain polarity
–Nonpolar neutral (Hydrophobic): Glycine, Alanine, Valine, Leucine, Isoleucine, Proline, Methionine, Phenylalanine
–Polar neutral: Serine, Threonine, Cysteine, Asparagine, Glutamine, Tyrosine, Tryptophan
–Polar acidic (AKA Negatively charged amino acids, AKA acid amino acids): Aspartate, Glutamate
–Polar basic (AKA positively charged amino acids, AKA basic amino acids): Lysine, Arginine, Histidine
Other classifications consider also different subgroups, or even can include amino acids of different groups, based in other common chemical characteristics. Examples of these amino acid subgroups are:
• Aromatic amino : Tyrosine, Tryptophan, phenylalanine
• Amino acids containing Sulfur: Cysteine and Methionine
• Amino acids with Hydroxyl group: Serine, Threonine, Tyrosine
• Branched chain amino acids: Valine, Leucine, Isoleucine
The best way to be able to classify an amino acid is by knowing the chemical structure. If the structure is known, it is possible to answer any question related to amino acid classification. I strongly recommend studying the individual amino acid structure of protein amino acids, in order to be able to understand the influence of mutations in the functionality and electrophoretic behavior of proteins, as we will see in next weeks.