DNA binding properties of mtSSB and E. coli SSB were assessed by electrophoretic mobility shift assay. Binding mixtures (20 μL) contained 15 mM HEPES-KOH (pH 7.6), 0.5 mM EDTA, 1 mM dithiothreitol, 50 μg/mL acetylated BSA, 40 fmol of 32P-labeled 34mer, and the indicated quantities of E. coli SSB or human mtSSB. Bound and unbound oligonucleotides were resolved on 10% native polyacrylamide gels and exposed to a phosphor storage screen. Radioactivity was imaged on a Typhoon 9400 phosphorimager and quantified with NIH Image software.