Fig. 6. The cleavage activity of the PK hammerhead ribozyme, and the effect of dG8 substitution and absence of magnesium ions.

A schematic of the construct (left) shows the two-piece ribozyme plus substrate (cleavage site arrowed), radioactively [5’-³²P]-labelled at the 5’ terminus of the substrate. Ribozyme incubations are shown on the right for wild-type and dG8 PK hammerhead, showing separation of substrate and product by polyacrylamide gel electrophoresis under denaturing conditions as a function of time of incubation. Reaction progress is plotted as a function of time (lower) for wild-type (circles) and dG8 ribozyme (diamonds) in the presence of magnesium ions, and wild-type ribozyme in the absence of magnesium ions (squares). The data have been fitted to single exponential functions from which the rates of reaction have been calculated (Table 1). See also Supplementary Fig. S7 for uncropped gel image.