First X-Ray Diffraction Image of a Single Virus

KentuckyFC writes "X-ray crystallography has been a workhorse for chemists since the 1940s and 50s, revealing the 3D structure of complex biological molecules such as haemoglobin, DNA and insulin. But the technique has a severe limitation: it only works with molecules that form into crystals and that turns out to be a tiny fraction of the proteins that make up living things. But today, a team of US researchers say they have created the first image of a single uncrystallized virus using x-ray diffraction. The trick is to take a diffraction pattern of the virus and then subtract the diffraction pattern of its surroundings (abstract). The breakthrough paves the way for scientists to start teasing apart the 3D structures of the many proteins that have eluded biologists to date."

Comments

overreaching /. summary

[jschen]

This work is really cool, and it's interesting to muse about what else might be imaged this way. But while 22 nanometer resolution may give insight into the structure of a virus, that would be awfully lousy resolution for a macromolecule (say, a protein) or even a macromolecular complex.

Re:overreaching /. summary

[damn_registrars]

while 22 nanometer resolution may give insight into the structure of a virus, that would be awfully lousy resolution for a macromolecule (say, a protein)
You hit the nail on the head, there. Indeed, protein structures generally need to be solved at a resolution of 8 angstroms or less to be taken seriously. And of course there are 10 Angstroms to a nanometer, so 22 nanometer resolution is equal to 220 Angstroms.

Useful for a virus superstructure, but with a protein you wouldn't be able to distinguish one end from another.

Impressive

[seanellis]

What I find impressive is that they were able to get detectable amounts of x-rays diffracted off a single virus, with no staining.

Re:First step towards X-ray microscopy

[Cevets]

Sorry, but people have been focusing x-rays for decades. As for x-ray microscopes, search up scanning transmission x-ray microscopy (STXM) or X-ray Photoelectron emission microscopy (X-PEEM), you should find them an interesting read.

Re:Makes sense

[Anonymous Coward]

I think you are confusing terms. Fatty acids don't refer to amino acids. While it is true that there are certain amino acids that are hydrophobic and hydrophilic (among other properties) like many fatty acids, this doesn't mean they are fatty acids themselves.

As far as the rest of your comment, it is confusing. I assume you are talking about the primary structure of the protein when you talk about 'fatty' and 'wet' amino acids (which I'm guessing you are trying to say that the side chains of the primary structure are hydrophobic and hydrophilic). But then you jump to the tertiary structure by talking about 'fatty' amino acids being surrounded by 'wet' amino acids. I really don't follow what you are trying to say. Many proteins have surfaces designed for certain conditions (like transmembrane proteins that have both hydrophilic and hydrophobic surfaces to anchor them in a phospholipid bilayer), and indeed, their surfaces in the tertiary structure do cover over parts that may not be desirable on the surface. Are you trying to argue that this is wrong?