On the interpretation and use of <|E|2>(d*) profiles

Profiles of squared normalized structure factors, (\E\(2)])(d*), have been computed for a large number of proteins and nucleic acids. These are interpreted in terms of their underlying structural features. It is also shown that the 'solvent dip' at around 6.3 Angstrom resolution is to a large extent a protein secondary-structure effect that is enhanced by the water structure. A hierarchical classification of protein structures based on their (\E\(2)) (d*) profiles is briefly outlined, together with the use of (\E\(2)) (d*) profiles as an improvement over Wilson absolute scale estimation and as a novel solvent-modelling method.