Question

For 2D NMR, X-ray crystallography, and Cryo EM, what level of protein structure can they resolve? Primary, secondary, tertiary, or quaternary? It can be multiple. So far I have tertiary and quaternary for X-ray crystallography, quaternary for Cryo-EM, and secondary and tertiary for 2D NMR but I am not sure about these.

Answer 1

According to the data base information around 90% of the protein structures have been determined by X-ray crystallography.

This method allows one to measure the three-dimensional (3-D) density distribution of electrons in the protein, in the crystallized state, and thereby infer the 3-D coordinates of all the atoms to be determined to a certain resolution.

Roughly 9% of the known protein structures have been obtained by nuclear magnetic resonance (NMR) techniques.

For larger protein complexes, cryo-electron microscopy can determine protein structures.

The resolution is typically lower than that of X-ray crystallography, or NMR, but the maximum resolution is steadily increasing. This technique is still a particularly valuable for very large protein complexes such as virus coat proteins and amyloid fibers.


Therefore one can use X-ray crystallography or Cryo-EM techniques to determine tertiary nd quaternary level of protien structure. In the same way it will be helpful to use 2D NMR or X-ray crystallography techniques for primary and secondary level of structures.