Hemoglobin Hb
Arwa Almejbel
Introduction
• First studied in the 1800th.
• Third of red blood cells is
hemoglobin.
• Found in bacteria ,eukaryotic
organisms and archea.
• The heme part is synthesized
in mitochondria and cytosol in
While the globin protein parts
are synthesized by ribosomes
in the cytosol.
• Function: to transport the
oxygen and maintain the
round shape of the RBCs.
Hemoglobin A Structure
α1
β2
Heme
β1
α2
Red is Heme , gray is α chain and blue is β
chain. PDB ID: 1HGA
Amino acid sequence Alignment
Glu6
Val62
His58
His87
Key amino acids in Hemoglobin
PDB ID: 1HGA
Oxygen binding
• Cooperative binding
• Binding to the 1st O2
facilitates the binding of
2nd ,3rd and 4th O2.
• Binding to O2 causes
conformational
changes.
. O2 . PHE . H2O . HIS . VAL
PDB ID: 1GZX
Oxygen-Hemoglobin binding
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Partial pressure of oxygen
determines how much oxygen
binds.
The affinity of O2 depends on PH.
Small amount of CO reduces Hb
ability to transport O2
https://thechronicleflask.wordpress.com/tag/red-blood-cells/
The T and R transition
T form
PDB ID: 1HGA
R form
PDB ID: 1BBB
Salt Bridges in Deoxy Hb
http://employees.csbsju.edu/hjakubowski/classes/ch331/bind/olbindhemoglobin.html
Mutations in hemoglobin (hemoglobinopathies):
Sickle cell anemia (Hb S):
http://www.cc.nih.gov/ccc/ccnews/nov99/
structure
PDB ID: 1GZX
Hydrophobic pocket
PDB ID: 2HBS
Val6, Leu88 , Phe85
• Lifetime of RBC in Sickle
cell is 20 days.
• As the cell sickle it
causes a low oxygen
conc. region.
• Lose of elasticity
• Unable to flow through
capillaries.
References
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Harrington, D.J., Adachi, K., Royer Jr., W.E. (1997) The high resolution crystal structure of deoxyhemoglobin S.
J.Mol.Biol. 272: 398-407
Shaanan, B. Structure of human oxyhaemoglobin at 2.1 A resolution. (1983) J.Mol.Biol. (171) 31-59
http://employees.csbsju.edu/hjakubowski/classes/ch331/bind/olbindhemoglobin.html
Marengo-Rowe,A. J. (2006) Structure-function relations of human hemoglobins. Proc (Bayl Univ Med Cent)19(3)
239–245.
Paoli, M., Liddington, R., Tame, J., Wilkinson, A., Dodson, G. (1996) Crystal structure of T state haemoglobin with
oxygen bound at all four haems. J.Mol.Biol. 256(4):775-92. PDB ID: 1BBB
Liddington, R., Derewenda, Z., Dodson, E., Hubbard,R, and Dodson, G. (1992) High resolution crystal
structures and comparisons of T-state deoxyhaemoglobin and two liganded T-state haemoglobins: T(alphaoxy)haemoglobin and T(met)haemoglobin. J Mol Biol. 228(2)551-79. PDB ID: 1HGA
Starr C., Taggart, R. (2001) Biology: The Unity and Diversity of Life (6th Ed.) pp. 183-227, Brooks/Cole, Pacific
Grove.
Rousseot, N., Jaenicke, E., Lamkemeyer, T., Harris, J.R., Pirow, R. (2006) Native and subunit
molecular mass
and quarternary structure of the hemoglobin from the primitive
branchiopod crustacean Triops cancriformis.
FEBS J 17, 4055-71.
Campbell, N.A., Reece, J.B., Taylor, M.R., Simon, E.J. (2006) Biology Concepts and Connections (Eds.) (5th Ed.) pp.
46-462, Pearson, San Francisco.
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P. (2002) Molecular Biology of the Cell. (Eds.), pp.
461, Garland Science, New York.
http://www.cc.nih.gov/ccc/ccnews/nov99/