METAL DECORATION OF BIOMACROMOLECULES AND MOLECULAR ASSEMBLIES - A REVIEW

Applications of metal decoration for the study of molecular assemblies and macromolecules of biological interest are reviewed. The principles of thin film formation and preferred cluster stabilization are discussed. On inorganic crystals decoration occurs on imperfections of the crystal surface. On proteins the metal distribution is related to the topochemistry of the molecule's surface. Two- or three-dimensional crystals of the molecules are needed to obtain an averaged decoration pattern but the possibility of applying decoration to non-crystalline specimens has been discussed. Decoration techniques have been used for the observation of periodic structures, e.g. lipid phases, and for the distinction of the two faces of bacterial membranes and bacterial surface layers. On frozen-hydrated crystals of enzymes molecular symmetries have been observed and first attempts to correlate decoration sites of different metals to molecular structure have been reported. The technique has been applied to support the packing analysis of protein crystals.