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5

You cannot solve a structure with a single frame, even with perfect diffraction. The reason you need images over a large swath of angles is because the diffraction pattern is also in three dimensions, in the so-called "reciprocal space". At minimum, a 180° rotation of the crystal is needed to sweep the entire reciprocal space sphere with the plane of ...


5

There are several factors that make obtaining crystal structures from membrane proteins more difficult. In brief, nearly every stage of obtaining the structure via crystallography is more difficult. First: protein expression. Large amounts of pure, well-folded protein are required and this is much more difficult to achieve than it is with a soluble ...


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Protein structures, which can be obtained from protein crystals or from concentrated solutions of pure protein via NMR, are arguably the primary source of knowledge that we have about how genes perform their function on the molecular level. I've added a link to RCSB.org above - they write up a story on an important protein structure monthly(?) - its a ...


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Hi sorry i missed this one - not too hard for "biology" If you look at a protein crystal (or any crystal really) in an x-ray beam, it scatters lots of spots (diffraction reflections). If you look at a picture of crystalline diffraction, at larger angles from the center of the x-ray beam, the reflections get weaker and weaker and basically just stop, if the ...


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Likely not. While one can get excellent diffraction data from a high quality crystal, it would be extremely difficult to solve the phase problem. The extra angles will help constraint the solutions.


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Not by analysing a single protein. There is work with x-ray lasers. You have to take a simultaneous image of millions of proteins and use that to get a structure. It's not quite prime time. People are also doing this with electron beams in electron microscopes. These methods will reconstruct 3D models of the molecules, sometimes in states which ...


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I always wondered this myself, but the structure of a protein can end up being quite important for a number of reasons. Most relate to the fact that protein function often depends on specific domains, and while a protein may have multiple functional domains it is important for all domains to be properly aligned and constructed in three-dimensional space. ...


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In many cases they are available. One of the establishing principles of the Protein Data Bank (PDB) was to store not only the models (atomic positions and identities) of macromolecules and proteins, but also the originating X-ray data, more recently in structure factors. If the question is 'why are they giving only the structure factors and not the ...


2

Expanding on something Amory said: They are very beneficial in drug discovery. This is because it is absolutely essential that you have a structure to do any sort of molecular dynamic simulation. In the early phases of drug discovery it is cheap and easy to do these types of experiments on a computer, rather than setting up an assay for different potential ...


2

Two questions here: 1) What does the symmetry of the crystal mean? The symmetry of the unit cell is the symmetry of the crystal. Its really useful thing to know about the crystal in practice. You can always pretend that any crystal is space group P1 - with no internal symmetry. This implies half of the diffraction data is needed to get a complete set. ...


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Just Download and Install: CCP4: Software for Macromolecular Crystallography



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