Re: what is hemoglobin structure and how it's affect sickle cell diseases ?

I'll give you just a bit of info on hemoglobin and sickle cell anemia and
then send you net-surfing as I found a few good sites (with better pictures
than what I could give you! :)

Most of my info is coming from Stryer's "Biochemistry" textbook:

Hemoglobin (the structure of which can be found here) is composed 
of four separate peptides: two "alpha" and two "beta" chains.  Each peptide
binds a heme molecule, which in turn positions the oxygen that hemoglobin
delivers to the tissues.  In a normal person, the red blood cell contains
a very high concentration of hemoglobin, but the individual hemoglobin
molecules do not interact. 

In sickle cell anemia, a single amino acid mutation (from glutamate to 
valine) in the beta chain causes one hemoglobin to "stick" to another
hemoglobin in low-oxygen conditions, eventually forming long fibers of
hemoglobin.  These fibers cause the red blood cell to sickle.
More info on sickle-cell disease, including why it can be beneficial in
some areas of the world can be found here.

Thanks for you question.

Michael Crawford
crawford@borcim.wustl.edu