Deoxyhemoglobin A
Deoxyhemoglobin S
Hemoglobin is a protein located within red blood cells. Its function is to transport oxygen from the lungs to the rest of the body. It also retrieves carbon dioxide transporting it back to the lungs. Normal hemoglobin structure contains both a tertiary and quaternary structures of a protein. The majority of the amino acids form alpha helices which are stabilized by hydrogen bonds. Its quaternary structure is formed by four globular protein subunits in a tetrahedral arrangement. Normal hemoglobin subunits contain 2 alpha chains and 2 beta chains which are arranged into Alpha-helix structured segments that bind to the non-protein Heme groups. Within the Heme group contains an iron charged ion which is the binding site of oxygen molecules.
Above the left picture is an example of “deoxyhemoglobin A” (“Deoxy”, when iron is not bound to any oxygen molecule). This is the typical shape of a normal hemoglobin molecule. The right picture is an example of deoxyhemoglobin S. This is a mutated hemoglobin molecule which is the cause for sickle cell disease. Sickle cell disease is a blood disorder brought on by abnormal hemoglobin forming a sickle shaped red blood cell.
Comparing these two photos helps you understand why the structure of proteins is so important to their function.
Sickle cell disease is a genetic disorder brought on by the mutation of the beta globin chain causing the hydrophilic amino acid glutamic to be replacing with a hydrophobic amino acid valine. When there are two abnormal Beta globin subunits bound to 2 alpha globin subunits, it will form Hemoglobin S.
http://en.wikipedia.org/wiki/Sickle_cell_disease
http://en.wikipedia.org/wiki/Hemoglobin
http://www.ncbi.nlm.nih.gov/Structure/mmdb/mmdbsrv.cgi?uid=1118
I found it very interesting that you chose hemoglobin as your protein as i had no clue at all what its structure was like. I didn't think it would have both secondary and quatranary structures as well but after reading this i can see why especially in the quatranary structures as iron is very important to humans. But I also liked how you have the two pictures up so one can see the difference betweeen the protiens hemoglobin and deoxyhemoglobin as i would have thought they would have been more simialr than they are but there is a big difference between the two. But in all nice entry and keep up the good work.
ReplyDeleteThank you!
ReplyDeleteI actually enjoyed learning about this as well. I was learning about the circulatory system in my anatomy class at the time of this post. It was very helpful to see what makes up a hemoglobin because you can see why its structure is the reason why it can function in such a way. Thanks for the post!