Explain what bonds exist in the tertiary structure of proteins

The tertiary structure involves folding of the α-helix secondary structure, creating a more complex 3D structure. Along with peptide and hydrogen bonds, new bond types exist at this level. One type is disulphide bonds, which exist between sulphur atoms on the amino acids cysteine and methionine. Another way protein shape is maintained is through the interaction of hydrophobic (water repellent) groups that aggregate, contorting the protein’s shape. Finally, negatively and positively charged groups from different amino acids can interact, forming ionic bonds. These bonds are important in maintaining the structure of globular proteins, such as digestive enzymes.