Table of Contents

Building blocks of proteins

General structure of amino acids. Keep in mind that at physiological pH, carboxylic and amino groups are ionized.

Proteins are composed of monomers called amino acids. Amino Acids are hydrocarbons that have an amino group (-NH2) and an acidic carboxyl group (-COOH). The R group represents a hydrocarbon chain with a modification that alters the properties of the amino acid. 20 universal amino acids are used to construct proteins. The variation in functional groups along the amino acid chain gives rise to the functional diversity of proteins.

20 amino acids and the non-universally found selenocysteine.

21 amino acids. The pKa of the functional groups of the side chains indicates what will be the ionization state at physiological pH.