Cryo–electron microscopy

[John Clark]

If you know the shape of a protein you can figure out how it works, the traditional way of doing it is to crystallize the protein and then use x-ray diffraction, but many important proteins can't be crystallized such as those in ribosomes and in cell membranes. An alternative method is Cryo–electron microscopy, It involves flash freezing the protein and then taking many electron microscope pictures of it from random angles and stitching all that information together with software to make a 3-D picture, but until now the resolution wasn't good enough to see individual atoms. In the October 21, 2020 issue of Nature there is a report of a Cryo–electron microscope that, thanks to an improved electron beam and improved software, has a resolution of 1.25 * 10^-10 meters, and that's good enough to see an individual hydrogen atom.  This should revolutionize the study of proteins structure and their function.

Atomic-resolution protein structure determination by cryo-EM

John K Clark

[Brent Meeker]

But doesn't the folding, and hence the shape and functionality, of a protein depend on environmental factors like, being in water, the pH, and even in some cases helper molecules?

Brent

--
You received this message because you are subscribed to the Google Groups "Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email to everything-li...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv0_F3H5YtbQG89%3DuYGC-Too2znA74sjPv5CX%3DzfajKSaw%40mail.gmail.com.

[Lawrence Crowell]

It appears to be in some ways more akin to tunneling electron microscopy. The molecule has a sort of "quantum atmosphere" that can be proved by its quantum effects. I had thought some years ago it was possible to probe this with how it destructively interferes a quantum wave. This appears to border on that sort of physics. 

I was once asked how a quantum particle interacted with a quantum barrier. It is the standard QM problem to compute the amplitude of a quantum wave impacting a potential barrier. The question pertained to how does this happen; is it some sort of interaction. I figured it was destructive interference with the quantum atmosphere of the barrier, at least for the so called infinite potential barrier, where for the finite barrier the destructive interference is not complete. 

LC

[John Clark]

On Thu, Oct 22, 2020 at 4:31 PM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

> ? But doesn't the folding, and hence the shape and functionality, of a protein depend on environmental factors like, being in water, the pH, and even in some cases helper molecules?

Yes and that's the beauty of it, the shape of the protein can be determined in all sorts of conditions not just when it's in the crystallized form.  And some proteins change the shape as they perform their catalyzing function so you can make a movie of it.

John K Clark