Figure 3.

Holoenzyme cutting by σ⁷⁰ single-Cys FeBABE conjugates. Immunostained blots of SDS/PAGE detecting either β or β′ subunit fragments by using affinity-purified N-terminal antibodies. (Left) Cleavage of the β subunit. (Right) Cleavage of the β′ subunit. Holoenzyme cleavage reactions that contained FeBABE-modified σ⁷⁰ proteins are indicated by a plus sign, and those that did not carry the FeBABE probe are indicated by a minus sign. All samples were treated with ascorbate and hydrogen peroxide (whether conjugated or not). Immunostained sequence markers prepared by cleavage at methionine and/or cysteine are shown along the right side of each gel. Broad range molecular weight markers, stained with Coomassie blue, are shown along the left edge of each gel.