First X-Ray Diffraction Image of a Single Virus 57
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."
The nobel prize goes to :D (Score:1, Offtopic)
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...because all those that contracted HIV from a bunk blood transfusion had a behavioral problem. Same with rape victims too, huh?
HIV is not necessarily a behavioral problem.
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Makes sense (Score:1, Interesting)
If you look at the density of a protein (which is pretty much all of a virus) it looks like a crystal. The common high school idea of a protein as a drop of fatty amino acids surrounded but wet amino acids is very false.
I wonder when they will start imaging other proteins?
This could be a boon to proteinomics!
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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
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That is exactly what I am arguing is wrong.
The internal consistency of a protein more closley matches a very tight crystal than a hydrophobic amalgum.
It is absolutly true that hydrophilic amino acids are often on the surface except for specific circumstances like you mentioned. However these amino acids tend to adopt the most energetically efficient form possible which is usually crystaline.
What I was refering to is that for most of modern biology there was an assumption that since the consistency of the i
Which high school was that? (Score:2)
What I was refering to is that for most of modern biology there was an assumption that since the consistency of the individual hydrophobic amino acids was very much like a oil that therefore the internal consistency of the protein should be similar.
That's weird, I never heard anything like that in high school biochemistry or college biology.
A more detailed analysis of densities, x-ray diffraction, fNMR and computer modeling proved that the internal structure of a protein is actually a very hard crystal with
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Actually refolding is fairly rare and almost always results from an environmental change (the protein get shoved into a membrane or it is surrounded by chaperon proteins). There are hinges and the like which affect functionality but thoes are very specific domains typically including a proline which isn't really an amino acid. Whole sale spontaneous refolding is essentially unheard of.
I went to a public high school and an engineering college. I heard the oil-drop model of proteins until I took biochem as
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Conceded. Protein's primary amino acid structure is too random (in most cases) to trully form a crystal.
But it is still cystaline. The local environment of most atoms resembles a cyrstal even if the more macro level does not.
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The reason X-ray diffraction needed a regular crystal not because it was impossible to get information but because there are limits on sensitivity and computation.
The first protein that X-ray crystallography was successfully used on was myoglobin. The processing included housewives recording the position of small,medium and large dots.
Now the sensitivity is much higher and the processing ability is astounding. This article is saying that they have figured out how to isolate the x-ray signal from a single
overreaching /. summary (Score:3, Informative)
Re:overreaching /. summary (Score:4, Informative)
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.
Not necessarily a overreaching /. summary (Score:2)
There are a lot of protein superstructures in the body. Many of them are larger than viruses. I am thinking immune cell communications, mitrocondrial kreb cycle, ribosomes etc.
This system can be used to eveluate the actual difference a point mutation makes. That will allow better models of protein folding and therefore more accurate predictions of final protein function.
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Could they get better resolution by using gamma rays, or (besides the radiation hazard) is there a technical problem with using higher-frequency photons?
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No, dipshit, I asked if resolution could be improved with higher-freq light. Learn to read.
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Not to dismiss their work, in fact this may be very helpful for all these huge complexes where you're not even close to get nicely diffracting crystals.
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This is actually a very important point. The limiting factor in pretty much any coherent diffractive imaging (CDI) experiment is the angle to which one can measure scattering. This angle depends strongly on the wavelength of the light and the size of the detector: shorter wavelengths and larger detectors get you better potential resolution.
Whether or not you can measure scattering to the highest possible angle is often another question entirely. In particular, for biological specimens, there appears to
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from TFA:
First step towards X-ray microscopy (Score:2, Informative)
This is very exciting, I remember during my Biophysics training that "blah, blah, blah you cannot focus X-rays like you can visible light with lenses, so we'll never have an X-ray microscope." Well, this looks promi
Re:First step towards X-ray microscopy (Score:4, Informative)
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While the statement "you cannot focus X-rays like you can visible light with lenses" is misleading, it's true. You can't focus X-rays like you can focus visible light, and you can't do it (effectively) with lenses. However, you can focus X-rays.
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While the statement "you cannot focus X-rays like you can visible light with lenses" is misleading, it's true. You can't focus X-rays like you can focus visible light, and you can't do it (effectively) with lenses. However, you can focus X-rays.
Yeah, you just use zone plates.
Anyway, the GP is correct in saying that x-ray microscopy is nothing new. The technique in TFA is not microscopy. My understanding (just from skimming the abstract, mind you) is that this is x-ray scattering, which is physically equivalent to taking a fourier transform of the sample, followed by subtraction of the scattering image from a black sample cell, and then an inverse fourier transform to get back to a position-space image of the virus.
Maybe I'm being dim, but I can
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Yes, neither x-ray microscopy nor x-ray diffraction are new. This appears to be essentially small-sample x-ray diffraction, as you describe.
TEM of biological materials (like a virus or protein) is tricky because the TEM can destroy the structure of the protein and can't adequately discern its internal structure. I'm less familiar with SEM, so I couldn't say, but diffraction is usually interesting not for obtaining an image of the sample, but determining its structure.
And yeah, you use zone plates. Or, for s
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SEM imaging is not going to offer much improvement over TEM. The main advantage of a SEM is that you (usually) look at the electrons scattered from the surface instead of having to transmit the electrons through the sample. This does have some important advantages - you don't need to thin samples, and you can use lower electron energies. Lower electron energies might lead to less damage, but all that energy is deposited right at the surface. Plus, you only end up imaging the surface, which is why it's us
Impressive (Score:4, Insightful)
What I find impressive is that they were able to get detectable amounts of x-rays diffracted off a single virus, with no staining.
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I think you're a little confused at how light at xray wavelengths work and diffraction in general.
This is huge development (Score:3, Funny)
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ring nebula (Score:2)
...looks like one of these [google.com]
(burning karma at a rate of ten)
Teasing apart the viruses (Score:1)
And you thought you had it hard back in high school.
Could you get a better image (Score:1)