Protein Folding

I'm currently in the process of going through a monstrous stack of periodicals I've accumulated, including the magazine Physics Today, which comes with my APS membership.

This article by Ashley Smart is simply a research summary on experiments on proteins.

But Smart evoked a lot of thoughts about proteins. We need them to be folded correctly to work, but how are they folded? How is this the minimum energy state.

Smart's description of various denatured (unfolded) proteins reminded me a lot of the language used in the glass/jamming community. A fried egg consists of proteins denatured by heat. A similar transition happens for
"glassy" systems: raise the temperature and the material will flow.

Mechanical stress can cause also cause the protein in egg white to denature, resulting in a foamy, stiff, meringue. In jammed systems, like mayonnaise, mechanical stress (i.e. using a butter knife) causes the material to unjam (i.e. deform and spread on the sandwich).

The third variable discussed in the jamming community is volume fraction, which I won't delve into here. The third variable for the egg example is acidity, mixing egg whites with lime juice will also cause the proteins to denature. Completely different, can't win 'em all.

What also drew me into this simple piece was the description of the experiments. (Smart does a commendable job of trying to explain the math in words.) There are two processes that contribute to the overall signal the researchers measure, only one of which relates to protein folding. But if you change the temperature, each process responds on a vastly different timescale.Taking measurements at the right frequency and using a trick of derivatives, they can isolate the process of interest. An experiment like this would be a great lab in a biophysics class.