Human Oxyhemoglobin Deoxyhemoglobin, published: friday 10th june 2016 by CLIC and WEB. As illustrated in this video and this 3D model, the oxygen molecule is shown in blue. As it binds to the iron atom in the center of the heme, it pulls a histidine amino acid upwards on the bottom side of the heme. This shifts the position of an entire alpha helix, shown here in orange below the heme. This motion is propagated throughout the protein chain and on to the other chains. The two structures shown (oxy/deoxy) have been model in 3d from PDB entries : 4hhb and 1hho (x5 000 000).