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Topic: How to imagine a Resolution of 2.a Angs.? in x-ray structures  (Read 1832 times)

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Offline sideeffect

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How to imagine a Resolution of 2.a Angs.? in x-ray structures
« on: December 12, 2012, 07:59:53 AM »
Hello.

Idont really know the meaning if: a structure of a protein for exemple is represented/analysed/resoluted with a resolution of 2.0 A.

in the case of displays its easy to imagine. A display has a resolution of AxB pixels.

but what about here, what are we looking at?
does it maybe mean this: (in the case of a resolution of 2.0 Angs.)
We can tell with a (99%-100%) certainity, that we will find a electrondensity in a square/cube of sidelenght 2.0 Angs.?


with regards

Offline curiouscat

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Re: How to imagine a Resolution of 2.a Angs.? in x-ray structures
« Reply #1 on: December 12, 2012, 12:15:16 PM »
Roughly speaking, you won't be able to discern any features that are smaller than 2 Å. Though at that sort of resolution you really are talking about individual atoms.

Online Babcock_Hall

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Re: How to imagine a Resolution of 2.a Angs.? in x-ray structures
« Reply #2 on: December 13, 2012, 03:13:26 PM »
Resolution should not be confused with the uncertainty in atomic position of the atoms in the protein, which is probably much smaller.  Gale Rhodes' book "Crystallography made crystal clear" might help.

Online Babcock_Hall

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Re: How to imagine a Resolution of 2.a Angs.? in x-ray structures
« Reply #3 on: December 13, 2012, 06:12:16 PM »
Some general biochemistry textbooks also have helpful figures.  For example Geoffrey Zubay, Biochemistry, 4th edition, Figure 5.45, p. 109, shows a contour representation of electron density at four resolutions.  Also, Berg's updating of Streyer's textbook has a nice use of the diffraction pattern of the Parthenon, and two reconstructions of the Parthenon from this diffraction pattern, one at low and one at high resolution.

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