Protein structures

Proteins fold spontaneously into complex 3-dimensional structures in salt water at room and body temperatures, and they are not only critical for life (and mis-folding critical causes of disease), but also stunningly beautiful to behold! You can spend hours on the World Wide Protein Data Bank (wwPDB), looking at various structures. Play around with these below! You can rotate and enlarge the structures. Notice the various secondary structures such as \(\alpha\) helices (purple) and \(\beta\) sheets (yellow), which are formed by hydrogen-bonding between residue’s amide and carbonyl groups.

Myoglobin (1mbn)

This is one of the proteins responsible for binding to O₂ and CO₂ using the Fe-binding molecule protoporphyrin. Myoglobin is significant in the study of protein structure, as it is the first protein to be solved via x-ray crystallography in 1957.

Chaperone (1dkz)

Proteins natively fold in salt water, but some stresses including high temperature can cause them to unfold. When that happens, the cell need machinery to refold mis/un-folded proteins… the chaperones! They are responsible for binding to the unfolded regions, which helps the rest of the protein to begin to fold again.

K\(^+\) channel (6v38)

Potassium (K\(^+\)) channels are remarkably important for their role in the action potential, the symphony-like cascades of sodium and potassium ions into and out of neuron cells, or muscle cells. I have spent a lot of time studying this particular potassium channel. Examine the 4-fold symmetry. See if you can find the \(\alpha\) helix-rich transmembrane domain that houses the pore and potassium selectivity filter. There is also a large domain that sits beneath the membrane inside of the cell.