Tertiary Structure
Tertiary structure of an enzyme.
Note beta sheets (yellow ribbons) and alpha-helices (pink helices). The 3D surface
is also shown.
The secondary
structures fold into complex, three-dimensional shapes. The main driving force
in the formation of tertiary structure is the burying of hydrophobic residues.
In this way, ‘oily’ amino acids are hidden from the surrounding water by
placing them at the core of the protein structure.
Cut-away view showing hydrophobic core (dark) and Surface view showing hydrophilic surface (light)
Two views of the same
protein showing the location of hydrophobic and hydrophilic residues.
Other bonds involved in tertiary structure are hydrogen bonds, electrostatic bonds (‘salt bridges’), and covalent disulphide bridges. Proteins intended for harsh environments outside the cell have stronger bonding to hold their tertiary structures together.
Fictional peptide showing two disulphide bridges, a salt bridge, and inter-residue hydrogen bonding.
Primary structure & introduction
Quaternary structure & summary