Structural information of proteins have shown to be of critical importance in the discovery and development of pharmaceuticals. Membrane proteins such as ion channels and G-protein coupled receptors constitute a sizeable fraction of human genes and are targeted by approximately 60% of drugs that are currently on the market. Determinatinations of the 3-D structures of membrane proteins have lagged far behind the determination of structures of soluble proteins. A recently developed technique for membrane protein crystal growth involves the use of a crystallization matrix that consists of a lipidic cubic phase in which the membrane protein crystallizes in a microenvironment resembling native lipid bilayers. So far only colored membrane proteins have been crystallized using this method. This is partly due to the ease of detection of colored crystals in an otherwise colorless background. Though optically transparent and non-birefringent, the detection of non-colored crystals in these lipidic phases poses a challenge. The reason for this lies in the generally small size of crystals (sometimes less than 50 micrometers), in their low contrast and in optical obstructions caused by lipid phase transitions that may occur during the course of the crystallization experiment. The goal of this project is to develop a microscope-based imaging technology that alleviates this limitation. It is proposed to construct an automated, digitally enhanced cross-polarization microscope for the detection of colorless microcrystals. Ultimately this digital contrast enhancement technology will allow fast and efficient detection of non-colored membrane protein crystals in crystallization trials. ? ?
