The Jmol image is based on pdb file 1MBO Myoglobin is an oxygen binding protein found in muscle tissue. Myoglobin shares many characteristics with its oxygen binding siblings. All have a distinctive fold that holds the heme group in place, protecting the ferrous ion from oxidation. (Iron must be in the +2 state for the heme group to bind properly to oxygen).

This is a myoglobin molecule (1611 atoms) showing the groove in which the heme group sits. In this model, the polar residues are pictured in blue; the red residues indicated nonpolar amino acids. This polar exterior and nonpolar interior is typical for all globins.

This is the same model as the last except for the heme group shown in the groove. The heme group is shown in gray. Notice the gold oxygen molecule bound to the heme group, but safely tucked away so that it doesn't cause oxidation before the desired location.

Here is another spacefilled model of myoglobin. This time green represents the polar residues and blue the nonpolar ones. The heme group is in pink, while oxygen is red. Notice how neatly the oxygen molecule is packed away.

This is a backbone model illustrating the 8 different helices that make up the myoglobin molecule. The groove which houses the heme group is between the E(pink) and F(purple) helices.

Another backbone version of the helical structure of myoglobin, showing the hemoglobin in groove between the E and F (pictured in blue helices). The heme group is shown in cpk colors and the bound oxygen(O2) is colored firebrick red.

Another backbone version this time highlighting some key proximal and distal residues. The proximal histidine is colored lime green. The key distal shown are the distal histidine shown in yellow, the valine is in cyan and the phenylalanine in deep pink

The same backbone model highlighting some of the key proximal and distal residues with the heme group and bound oxygen in place.

This models highlights the invariant or nearly invariant positions found in nearly all globins (see biology discussion link below). The yellow residues show the invariant nonpolar amino acids, the blue residues show the invariant polar(or ambivalent) amino acids, the orange the almost invarent nonpolar amino acids and the cyan the nearly invariant polar or ambivalent amino acids) Orange Almost invariant nonpolar Cyan Almost Invariant polar or ambivalentsame backbone model highlighting some of the key proximal and distal residues with the heme group and bound oxygen in place.

Citations: Watson, H.C., 1969. The stereochemistry of the protein myoglobin. Prog. Stereochem, 4(299), p.5. http://www.rcsb.org/pdb/explore/explore.do?structureId=1mbn http://www.rcsb.org/pdb/explore.do?structureId=1MBO http://www.biologydiscussion.com/molecular-biology/vertebrate-hemoglobins-structure-function-and-action-with-diagram/3069