VISUALIZING ENZYME AND RIBOZYME INTERMEDIATES USING FAST DIFFRACTION AND REACTION TRAPPING METHODS

Using mutatagenesis, steady-state trapping, and photoactivation of cag ed substrates in two separate series of experiments, we have determine d the structures of three sequential intermediates formed by the enzym e isocitrate dehydrogenase. Using pH triggering and physical trapping (flash-cooling), we have determined the structure of an unmodified, fu lly reactive hammerhead ribozyme construct at two separate stages of t he autolytic cleavage reaction, and have proposed a structural mechani sm for transition state formation.