1958-1959

Protein crystallography

• The first proteins whose structures
• were determined by X-ray crystallography
• were myoglobin,
• the protein that stores oxygen
• in animal muscle tissues,
• and hemoglobin,
• the protein that transports oxygen
• in the bloodstream.
• John Kendrew and Max Perutz
• studied hemoglobin from sheep
• but were not able to make much progress.
• Obtaining myoglobin from a whale,
• which formed crystals that were large enough,
• Kendrew and Perutz compared
• X-ray diffraction patterns
• of various samples
• infused with different metals.

The structure of myoglobin

• A myoglobin is a polypeptide
• with eight connected right-handed alpha-helices.
• Hydrophobic amino acid groups
• are packed in myoglobin’s interior
• and hydrophilic amino acid groups
• are exposed on its surface.
• One heme prosthetic group
• is packed into a hydrophobic cleft.
• Each heme group has one iron atom
• that binds to an oxygen atom.

The structure of hemoglobin

• A hemoglobin contains four polypeptide clusters
• alpha, beta, gamma, delta,
• each containing the same kind of heme prosthetic group
• found in myoglobin.

Red-blooded

• The red color of blood
• doesn’t come from the iron in it,
• but from the porphyrin to which the iron is bound.
• Nobody’s skin is naturally red
• and everybody’s blood is red,
• and the average person has average passions.
• Being a great singer or artist
• requires hard work and long study;
• being an American, only being born here.