Principles of Biochemistry

Amino acids consist of a central carbon atom chemically bonded to one hydrogen atom (H), one carboxylic acid group (-COOH) and one side chain 'R'. The side chain gives each amino acid its identity unique to each amino acid. It varies from one hydrogen atom in glycine to complex ring of carbon and hydrogen in phenylalanine.

In ∝-amino acids, both the amino and carboxyl groups are attached to the same carbon atom (∝-carbon). All the amino acids except glycine have an asymmetric carbon atom ( which four different groups are attached . The asymmetric carbon is a chiral center.