Figure 1.

Gp74-mediated digestion of lambda phage DNA in the presence of Ni²⁺ ions. Fractions containing gp74 from the Superdex 75 gel filtration column were assayed for endonuclease activity in the presence of Ni²⁺. The top panel shows the elution profile of gp74 from the Superdex 75 column. Fractions between 13.5 and 17.0 mL, indicated by dashed lines at the bottom of the trace, were tested. The bottom panel shows the agarose gel (1%) electrophoresis analysis of the digestion reactions from each fraction. Digestion reactions were allowed to proceed for 6 h. The concentrations of Ni²⁺ ions and lambda (λ) DNA in the reactions were 0.5 mM and 25 μg/mL, respectively. In each reaction, 26.3 μL of the gp74 fraction was used in a total reaction volume of 200 μL. A volume of 26.3 μL was chosen, so that gp74 concentration would be 24 μg/mL in the reaction corresponding to the elution fraction with the highest gp74 concentration. For the control reaction containing λ DNA and gp74 only, 26.3 μL from the fraction with the greatest amount of gp74 was used.