|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1998 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1997 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Successful fractionation of Biological membranes, including purification a membrane protein, is critical for structural analyses, and requires understanding of phase behavior of the multi-component solution system. We have studied one of the major biological membrane system, rod outer segments (ROS) of bovine retina, especially the effect of various factors (detergent, salt, pH, temperature, additives, etc) on the process of selective solubilization and three-dimensional crystallization of a membrane protein rhodopsin. The results of these studies are supposed to be useful for the perticular membrane systems where, being similar to the situation of ROS, the content of the reverse-cone-shaped lipid is substantial. In these systems, phase transition of lipid would affect the fractionation process, leading to the clear separation of the components. We have also tried to make three-dimensional crystals of bovine rhodopsin suitable for X-ray diffraction analysis. Two types of the crystals (bipyramidal and rod-shaped) were examined under cryogenic condition, using X-ray from synchrotoron source (Photon Factory BL6A, BL18B and SPring-8 BL41XU). The rod-shaped crystal diffracted X-ray beyond 5 A resolution along the direction parallel to the longest axis of the crystal. The number and the arrangement of rhodopsin molecules in the unit cell were also estimated. Further improvement of the cryoegnic conditions would be required for high-resolution structural analysis.