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Unlike other structure determination methods, with x-ray crystallography, there is no fundamental limit on the size of the molecule or complex to be studied. However, in order for the method to work, a pure, crystalline sample of the protein must be obtained. For many proteins, including many membrane-bound receptors, this is not possible. In addition,a single x-ray diffraction experiment provides only static information - that is, it provides only information about the native structure of the protein under the particular experimental conditions used. As we will see later, proteins are often flexible, dynamic objects when in their natural state in solution, so a single structure, while useful, may not tell the full story. More information on X-ray Crystallography is available at Crystallography 101 and in the Wikipedia .


Nuclear Magnetic Resonance (NMR) spectroscopy has recently come into its own as a protein structure determination method. In an NMR experiment, a very strong magnetic field is transiently applied to a sample of the protein being studied, forcing any magnetic atomic nuclei into alignment. The signal given off by a nucleus as it returns to an unaligned state is characteristic of its chemical environment. Information about the atoms within two chemical bonds of the resonating nucleus can be deduced, and, more importantly, information about which atoms are spatially near each other can also be found. The latter information leads to a large system of distance constraints between the atoms of the protein, which can then be solved to find a three-dimensional structure. Resolution of NMR structures is variable and depends strongly on the flexibility of the protein. Because NMR is performed on proteins in solution, they are free to undergo spatial rearrangements, so for flexible parts of the protein, there may be many more than one detectable structures. In fact, NMR structures are generally reported as ensembles of 20-50 distinct structures. This makes NMR the only structure determination technique suited to elucidating the behavior of intrinsically unstructured proteins , that is, proteins that lack a well-defined tertiary structure. The reported ensemble may also provide insight into the dynamics of the protein, that is, the ways in which it tends to move.

NMR structure determination is generally limited to proteins smaller than 25-30 kilodaltons (kDa), because the signals from different atoms start to overlap and become difficult to resolve in that range. Additionally, the proteins must be soluble in concentrations of 0.2-0.5 mM without aggregation or precipitation.For more information on how NMR is used to find molecular structures, please see NMR Basics and The World of NMR: Magnets, Radio Waves, and Detective Work at the National Institutes of Health's The Structures of Life website.

Electron diffraction

Electron diffraction works under the same principle as x-ray crystallography, but instead of x-rays, electrons are used to probe the structure. Because of difficulties in obtaining and interpreting electron diffraction data, it is rarely used for protein structure determination. Nevertheless, ED structures do exist in the PDB. For more on ED, see this Wikipedia article .

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Geometric methods in structural computational biology. OpenStax CNX. Jun 11, 2007 Download for free at http://cnx.org/content/col10344/1.6
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