Figure 3.

Investigation of mutations: (a) Relative catalytic activity of the differently combined modifications in positions 9 and 17. Gray column represents the wild-type. (b) Catalytic activity of the U17dU G9Pu double mutant in the presence of two different Diels–Alder products. (c) Lead probing PAGE gel of 5′-³²P-labeled wild-type, U17C and U17isoC mutant at different Mg²⁺ ion concentrations (0–10 mM). 'OH' and 'T1' correspond to alkaline hydrolysis and RNase T1 ladder, 'Ctrl' to control incubation (absence of lead ions). For precise assignment of the bands, compare Figure 6 in reference (10).