... polypep-tides, all the proteins of interest were present in the solublefraction of the induced cell in the case of the expression of pET22b(+)/touBEA and /touC, whereas the product of the expression of pET22b(+)/touF ... mass of about 10, 38 and 57 kDa, the expected molecular size of recombinant subunits B, E andA, respectively. The identity of the proteins was furtherchecked by N-terminal sequencing of the ... that the activity of the protein is strictly dependent on the presence of the ironcenter. In fact, when apo-Tomo F (which contains FAD)was used as a catalyst in the same assay, no activity wasdetected....