Tertiary Protein - Structure
Introduction:
The third type of structure found in proteins is called tertiary protein structure. The tertiary structure is the final specific geometric shape that a protein assumes. This final shape is determined by a variety of bonding interactions between the "side chains" on the amino acids. These bonding interactions may be stronger than the hydrogen bonds between amide groups holding the helical structure. As a result, bonding interactions between "side chains" may cause a number of folds, bends, and loops in the protein chain. Different fragments of the same chain may become bonded together.
There are four types of bonding interactions between "side chains" including: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions.
Disulfide Bonds:
Disulfide bonds are formed by oxidation of the sulfhydryl groups on cysteine. Review reaction. Different protein chains or loops within a single chain are held together by the strong covalent disulfide bonds. Both of these examples are exhibited by the insulin in the graphic on the left.
Insulin Protein - Chime in new window