Müller Crystall

Please explain the term crystallographic asymmetric unit (hint: the ‘problem with porin’ (see lectures)).

Why do protein crystallographer deposit the content of the asymmetric unit when they deposit a solved X-ray structure with the protein databank?

Please explain the formalism by which the packing of molecules in protein crystals is being described (space groups, bravais lattices, symmetry elements)

Please explain in a few sentences how the experimental structure of a protein can be derived by X-ray crystallography.

Can the same methods also be used for solving the structures of nucleotides or protein-polynucleotide complexes?

Can the same methods also be used for solving the structure of aspirin (acetylsalicyclic acid)?

Please explain how resolution affects the quality of crystal structures.

Please explain how resolution affects the ratio of observables versus refinement parameters during the determination of structures via X-ray crystallography.

What is the phase problem in X-ray crystallography?

Please name a method with which the ‘phase problem’ can be overcome

. Please name several criteria by which the quality of a structure determined by X-ray crystallography can be assessed

What information does the Ramachandran plot provide with regard to the correctness of an X-ray, NMR or cryoEM-derived structure?

What is meant by the phrase: (protein) crystal structures are underdetermined.