Schematic drawing of the affinity chromatography assay. The biotinylated (B) oligonucleotides bearing the AGAA-box were annealed and incubated with streptavidin particles tagged with a paramagnetic particle (S). Cell-free extracts from cells grown in glucose, containing the potential Xylanase promoter-binding protein (Xpp1), were added and incubated under the same conditions as those used for the EMSA (see Fig. 1). The Xpp1-DNA streptavidin complex was separated in a magnetic field according to the manufacturer's instructions (Miltenyi Biotec GmbH, Bergisch Gladbach, Germany).