Lab Techniques:
How are Structures Resolved?
Proteins fulfil a wide range of biological functions which depend upon their three dimensional structures. Therefore,
deciphering the structure of proteins has been the quest of scientists for
decades. The 3D structures of proteins can be experimentally determined at the atomic level by two
different methods, X-ray crystallography and NMR (Nuclear Magnetic
Resonance) Spectroscopy. Both techniques, combined
with computer technology, have allowed scientists to create atomic models
for protein structures that can be viewed and manipulated. Alternatively,
computer methods exist for predicting a structure from the linear sequence
of the protein, however, the confidence level of the results are low. The most
effective form of computational analysis models a protein structure based
on similarity to another protein structure that has been experimentally-derived.
| X-Ray |
Provides the highest resolution. Requires crystallization of protein and usually
gives only one model of structure. May be automated in future. |
| NMR |
Allows structure determination of protein in solution. Variability of solution
conditions possible. Provides characterization of intrinsic protein motion in solution. |
| Computation |
Simulates the action of the forces that act on each atom in a molecule of known
composition and approximates structure. Produces non-experimental models. Fast,
but presently least reliable. |
Source: slide from the Structure module, by Jennifer Lyon, of the 5-day NCBI Advanced Workshop for Bioinformatics Information Specialists
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