Reactivity of the DMS on the topoisomers of dsMCs in the absence or in the presence of magnesium.

(A) Comparison of the reactivity of three topoisomers (T0, T-3, T-4/-5) with DMS in the absence of magnesium. (B) Comparison of the reactivity of three topoisomers (T0, T-3, T-4/-5) with DMS in the presence of magnesium. [DMS] ranges from 0 to 0.125%. The % of covalently closed dsMCs is represented as a function of [DMS]. Error bars correspond to the standard errors calculated from three independent experiments.