Structure of heamoglobin?
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Hemoglobin belongs to a clan of heme-proteins which contain a heme prosthetic group. The best known heme is Fe-protoporphyrin IX. Other members of the family include: b-type and c-type cytochromes, catalases and peroxidases. The function of Hb is to transport oxygen to cells, and it has to do so keeping the Fe++ in the reduced state.
Hemoglobin is a tetramer consisting of 2 pairs of one and the same dimers, alpha1beta1 and alpha2beta2 subunits. Each of the 4 chains contains one heme group, in which the Fe ion is coordinated to the 4 nitrogen of the tetrapyrrole ring and the nitrogen of His87 of helix F. The sixth coordination site is free for ligating oxygen
Tetrameric Hb occurs in two conformations: the oxygenated T-state and deoxygenated R-state. The individual chains inside each dimer are tightly packed together, but the two subunits are reversibly held together by a multitude of salt bridges and hydrogen bonds contained by the deoxy state.
"Hemoglobin (also spelled haemoglobin and abbreviated Hb or Hgb) is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates,[1] and the tissues of some invertebrates"
"In most humans, the hemoglobin molecule is an assembly of four globular protein subunits. Each subunit is composed of a protein chain tightly associated near a non-protein heme group. Each protein chain arranges into a set of alpha-helix structural segments connected together in a globin fold arrangement, so call because this arrangement is the same folding motif used in other heme/globin proteins such as myoglobin.[14][15] This folding pattern contains a pocket which strongly binds the heme group" Source(s): http://en.wikipedia.org/wiki/Hemoglobin#…
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