Myoglobin includes a heme prosthetic group (a non-amino acid component of a functional protein). The heme is bound tightly in a hydrophobic pocket of the myoglobin. It is also bound by a covalent link between the "proximal histidene" (his93) of the protein. A second his (the "distal histidine" his64) is on the opposite side of the heme that restricts the space at the binding site, helping to decrease the affinity for CO relative to that of O2 (althought CO still binds much more tightly than does O2). As for all soluble globular proteins, hydrophilic amino acids are found mostly on the exterior, while the interior is largely hydrophilic.
Use the buttons above to see alternate views of the structure. You can manipulate the structure directly with the mouse (see Brief JSmol Instructions).
Copyright© Charles S. Gasser, 2010, 2013
Dept. of Molecular and Cellular Biology at the University of California, Davis.