A structural biology group wants to determine the packing arrangement of individual…
PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Crystal structure, bonding and diffraction · Crystal structure, bonding and diffraction
Solid State Physics, Ch Seeing atoms: electron and scanning-probe microscopy
Problem
A structural biology group wants to determine the packing arrangement of individual protein molecules within a small, roughly 200nm-wide, two-dimensional crystalline patch of a membrane protein sitting in a lipid bilayer, kept immersed in aqueous buffer throughout so that the protein retains its native conformation. The patch is too small and there are too few of them for a measurable X-ray diffraction pattern to be collected, and the lipid bilayer is electrically insulating.
((a)) Using the resolution figures and sample requirements for X-ray diffraction, transmission electron microscopy, scanning tunnelling microscopy and atomic force microscopy, eliminate the techniques that cannot do this job, giving the reason for each.
((b)) Identify the technique that remains, and quote the resolution figure that shows it is adequate to resolve individual protein molecules (which are several nanometres across).