CRYSTALS BUILT OF BIOLOGICAL MACROMOLECULES

A general view is presented on how biological macromolecules dissolved in aqueous solutions build crystals having in mind, first of all, dat a on protein crystals. It is demonstrated that these crystals are esse ntially very close to inorganic ones despite their major quantitative difference in properties. The ''trial and error'' mechanism controllin g the selection of species during inorganic crystallization seems not to be effective in proteins. Instead, mainly electrostatic recognition of proper attachment sites by molecules located close to the growing surface is expected. Defects in biocrystals are of the same type as in inorganic salts. Mosaicity of the grown biocrystals seriously deterio rate their practical use to reveal molecular structure by X-ray diffra ction. The onset of such mosaicity is discussed making use of epitaxy concepts.