Hemoglobin

3D Structure of Hemoglobin

CPK Color Scheme C O N P S

Hemoglobin is a protein in the blood responsible for binding oxygen in the lung and transporting oxygen throughout the body.

Hemoglobin consists of four distinct peptide chains. These four folded polypeptide subunits make up hemoglobin's quaternary structure. Click

here.

In each of the four subunits there is a heme-iron group. The heme-iron group gives hemoglobin its oxygen-binding and red pigment characteristics. Click

here.

For a better look at the heme groups located on the polypeptide chains, click

here.
And click

here for just the heme groups without the polypeptide chains. Each heme group contains one iron atom.

Click

here to see heme-iron groups colored by element.

Click

here for closeup of how iron is attached to the heme molecule.

Click here for a closeup spacefill view of a hemoglobin polypeptide chain (the heme-iron group is not spacefill, just the polypeptide chain).

Click here for an individual heme-iron molecule and see the atoms that make it up.

This image shows a closeup of one of the four heme-iron groups located on a deoxygenated hemoglobin. The iron atom(orange) is the binding site for oxygen. In this image, the iron atom is available for binding.

Sickle hemoglobin differs from normal hemoglobin by just one amino acid. The glutamate at position 6 is replaced by valine. This one amino acid change results in the creation of hydrophobic spots (shown white). The hydrophobic spots of different deoxygenated hemoglobin stick together forming chains of deoxygenated hemoglobin.

References:
Kogoy, John. Chime Manual. April 2003
Protein Data Bank. April 2003
Protein Explorer. April 2003
University of Massachusetts Microbiology - Hemoglobin. 10 March 2003