I am a staff crystalogapher for a chemistry department. This involves solving
structures for chemists (molecules which rarely exceed 200 hundred nonhydrogen
atoms ( this would be the extreme case)). My question is how does protien
crystallography differ. I understand the resolution is lower (~1.5 angstroms
versus ~0.8) and that instead of assigning atoms to the difference map, amino
acid residues asigned instead during refinements of the model. How do you
chose a residue and what is the justification? For me, I look at bond lengths
and angles, how could that apply to amino acid residues, I see no relation.
Also, a good structure for a compound has a R value of less than 6%, I have
seen publications of protien structures which exceed 30%. What is good for protiens?
