On this page we'll take a look at the tertiary structure of proteins.
You will find that it involves the interaction between the side groups of amino acid
residues from different parts of the same chain.
|A telephone cord, specifically the coil of a telephone
cord, can be used as an analogy to the alpha helix secondary structure of
|You know as well as I do, that telephone cords also have a tertiary
structure. The tertiary structure of a protein refers to the way the secondary
structure folds back upon itself or twists around to form a three-dimensional structure.
The secondary coil structure is still there, but the tertiary tangle has been superimposed
|The tertiary structure for myoglobin is fairly well understood and is
shown here. Myoglobin has an alpha helix which then can be viewed as being enclosed in
this blue sheath, the sheath doesn't exist but we can draw it that way. That helix folds
back upon itself into what's referred to as the tertiary structure of myoglobin. Bonds
between the side groups of the amino acid residues are responsible for holding together
the tertiary structure of this protein.
Bond Types Stabilizing Tertiary Structure
The kinds of bonds that can exist between the side groups include:
|Van der Waals bonds if the side groups are nonpolar.|
|Hydrogen bonds if the side groups contain hydroxyl or amino groups.|
|Ionic bonds if the side groups are acids and bases that can transfer
protons from one to another making a carboxylate ion, which is negative, and essentially
an ammonium or quaternary ammonium ion which is positive. |
|Covalent bonds if the side groups are cysteine residues in which the
sulfur atoms are bonded together by the removal of two hydrogen atoms. |
In summary, the tertiary structure of a protein is held together by the bonds formed by
the side groups, and there is quite a variety of different bonds that can cause the
tertiary structure to form.
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©2001, 2003 Clackamas Community College, Hal Bender