Figure 1: Domain structure of ubiquitin-specific proteases ... In these enzymes, a nearby His side chain lowers the pKa of a catalytic Cys, enabling a nucleophilic attack on isopeptide linkages.

The chemistry of amino acid side chains is critical to protein structure because these side chains can bond with one another to hold a length of protein in a certain shape or conformation.

They play a crucial role in the structure, function, and regulation of the body's tissues and organs. Amino acids are characterized by their central carbon atom, known as the α-carbon, which is bonded ...