Dear Crystallographers, what is the dogma with regard to affinities in crystals? For example, if I soak three crystals in 1pM, 1nM, and 1uM compound X, and they all show equivalent density, does that mean that the affinity is really better than 1pM, or is the crystal of such a high local concentration (~600mg/mL) that it will be fully occupied at nearly any concentration, provided external ligand concentration does not change due to binding in the crystal? I guess there is also the problem that the crystallization solutions are very non-physiological, but neglecting that, is there any straightforward way to think of this, or is there a good reference?
Jacob Keller -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: [email protected] *******************************************
