Formation of Two-Dimensional Crystals of Protein and Studies of Their Structure and Surface Forces

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The present research project is devided into two aims : 1.We should develop a method to crystallize a water-soluble protein (ferritin) in two dimensions on mercury and water surfaces. 2.The two-dimensional structure of the protein should be analyzed with the crystal, and an interaction force acting between two-dimensional crystal surfaces has to be measured in water.In the aim 1, a conventional type of a mercury trough was developed in the beginning year of the project. Feritin was successfully crystallized in two dimensions with the mercury trough on the last year in the project. At the same time, we examined the two-dimensional crystallization of the same protein on a water surface. The successful results on the water surface were obtained, and reported in a jounal, last year. In particular, the method on the water surface has been further developing as a new apparatus to control not only the water-soluble protein but amphilic compounds in two-diemsional densities and crystallization. In the aim 2, we found that both ferritin crystals on mercury and water reveal similar interior structure and crystaline form. A ferritin crystal in two dimensions was transferred onto cleft mica surfaces, and an interaction force between the crystal surfaces was measured by an surface force apparatus in water. As a result, the force indicated no long range forces such as electrostatic repulsion. Instead, we found a steric repulsive force due to the overlap between the crystal surfaces.In addition, an advanced method of electron microscopy was applied to study the structure of an ultra thin film of polymers. Physico-chemical properties in water and on a water surface and self-assembly structure in water of a new functional biosurfactant, which would be used for crystallization as open issues, were studied, and these were reported in a journal.