MET-MYOGLOBIN

Here is the structure of myoglobin, an oxygen-binding protein. The globin fold is found in many proteins and seems to represents natures way of designing a protein which can bind heme groups and serve as an oxygen carrier. It contains 8 helices (A-H) connected by short loops. The helices pack in a way that sequential helices are not packed next to each other. The helices form a hydrophobic binding pocket for heme. The angles at which the helices pack are in most cases around 50 degrees, so the packing is distinctly different than in the 4-helix bundle proteins. Side chains project from the helix axes. Packing of helices occurs when the side chains of 1 helix (which you can think of like a ridge) interact with another helix in the space between the side chains - effectively like grooves.