Relevance of three-dimensional reconstructions of stain distributions for structural analysis of biomolecules.

The relevance of a three-dimensional model of a protein molecule is discussed in the context of artefacts which inevitably occur during the preparation and imaging process. It is emphasized that even under optimistic assumptions, there-construction of a structure complementary to a given spatial stain distribution cannot, at resolutions below 10-15 A, be regarded as being identical with the real protein structure.