CHAPTER 19: Unit 5. Types of Proteins: Quaternary Structures

The figures below illustrate the structure of quaternary protein structures:

Reference: https://www.quora.com/What-are-the-4-structural-levels-of-proteins

Reference: https://courses.lumenlearning.com/boundless-biology/chapter/proteins/

As the figures above show, the quaternary protein structure is made of two or more amino acid chains.An example of the quaternary protein structure is the hemoglobin (human blood).The figure below illustrates the structure of the quaternary structure of protein (hemoglobin):

Reference: https://www.researchgate.net/figure/Structure-of-adult-hemoglobin_fig2_318764543

Reference:

The videos below illustrate the function and the structure of the hemoglobin.

Hemoglobin:

It is made of 4 chains: 2 alpha chains and 2 beta chains have different sequence of amino acids. These chains (subunits) are held together by the five types of interactions mentioned above.

Each chain contains a heme group that binds oxygen. All the chains (subunits) should be combined for the hemoglobin to function properly.

Hemoglobin is working in the blood vessels.

Reference:
https://www.youtube.com/watch?v=Qv-KExGKAYw

Myoglobin:

Myoglobin is made of a protein that is made of 154 amino acids. These amino acids form eight alpha helices connected to turns with an oxygen binding site.
Myoglobin has a heme group which is responsible for carry oxygen molecules to muscle tissues.
The video below illustrates the difference between the hemoglobin and myoglobin in the human body.

Reference:
https://www.youtube.com/watch?v=Qv-KExGKAYw