User:Michael Roberts/BIOL115 Myo

MOLECULAR MODEL:

The initial view here is a ball-and-stick representation of the molecular structure of myoglobin.

SECONDARY STRUCTURE:

This next view simplifies things, and just shows a of the secondary structure of the protein.

You can visualise the hydrogen bonds that maintain the secondary structure of the protein by using the following menu command: Right click over the molecule window, then select: Style > Hydrogen bonds > Calculate.

THE GLOBIN FOLD:

In this next view, the eight are each coloured differently. This gives you an impression of the classic globion fold. The α-helices pack together tightly, and there is very little space in the centre of the protein.

HYDROPHOBICITY:

Globular folds like this are characterised by a polar, , which interacts with the aqueous solvent, and a hydrophobic core.

Hydrophobic, Polar

The next view shows a section through the protein that highlights the better.

This view has been produced in the software by a process known as 'slabbing'. You can still rotate the molecule around - whatever view you see will the the front part of the view of the protein cut off.

THE HEME GROUP:

Now let's turn our attention to the main function of myoglobin - oxygen binding.

Oxygen is bound by a , which sits in a hydrophobic pocket in the myoglobin protein.

Central to the heme group is an .

PROXIMAL AND DISTAL HISTIDINES:

The iron atom sits either side of the side chains of two .

One of these (coloured cyan) is attached to the iron atom, and is known as the proximal histidine. The other (green) is called the distal histidine.

OXYGEN: The space between the iron and the distal histidine is where the binds.