Analysis of the interaction between nusA-A1(Cys) and NusA by sandwich ELISA. nusA-A1(Cys) was conjugated to maleimide coated microtiter wells of 96 well strips via the lone C-terminal Cys, at 5 µg/ml. Dilutions of biotinylated-NusA were incubated on the strips, washed, and then incubated with Streptavidin-conjugated HRP and developed with TMB Ultra. Reactions were stopped with H2S04 and absorbance measured at A450. The blank wells were processed the same, except they included no nusA-A1(Cys).