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Prof. Eric Arnoys

Chem 324 - Biochemistry II

Protein of the Week: hemolysin


Hemolysin's beauty is undeniable (PDB code 7AHL, structure generated with PyMOL). The β-barrel in the bottom stalk traverses the membrane, with the mushroom-like cap perched on top.

hemolysin, top view

Another view, this time from the top of the structure, reveals its wonderful symmetry. In order to determine whether the β-barrel provides a channel through the protein, we need to examine a space-filling model:


Indeed it does. Here we once again see the symmetry of seven subunits that unite to form the complete structure.

hemolysin, bottom view

When we view the space filling model from below, we see the beautiful interplay of the subunits in forming its transmembrane β-barrel.

However, the hemolysin's name provides vital clues to its function: Staphylococcus aureus inserts hemolysin into the membranes of red blood cells, resulting in their rupture, leading to potentially fatal episodes of meningitis, pneumonia, and toxic shock. In his poem “The Tyger,” William Blake asked of the powerful predator — “Did he who made the lamb make thee?” How would you answer Blake if he asked that question of hemolysin in S. aureus?

“The Tyger”
William Blake

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?

In what distant deeps or skies
Burnt the fire of thine eyes?
On what wings dare he aspire?
What the hand dare seize the fire?

And what shoulder, and what art,
Could twist the sinews of thy heart?
And when thy heart began to beat,
What dread hand? and what dread feet?

What the hammer? what the chain?
In what furnace was thy brain?
What the anvil? what dread grasp
Dare its deadly terrors clasp?

When the stars threw down their spears,
And watered heaven with their tears,
Did he smile his work to see?
Did he who made the Lamb make thee?

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Dare frame thy fearful symmetry?



Minor in Biochemistry

Minor in Chemistry


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