TCEP hydrochloride has been introduced which o€ers the prospect of serving as an alternative to the more commonly employed DTT in the NF-κB-DNA binding reactions in vitro, using recombinant p50 protein and a 32 P-labelled κB oligonucleotide. DTT promotes NF-κB-DNA binding in concentrations from 0.25 to 2.6 mM in binding reactions. However, in the presence of 0.25 mM DTT, inhibition of NF-κB binding is seen only at Hg 2+ concentrations greater than 100 μM and results are highly variable. In contrast, TCEP hydrochloride promotes NF-κB-DNA binding in a dose-related manner in concentrations from 0.25 to 6 mM. In the presence of even 6 mM TCEP hydrochloride, Hg 2+ prevents NF-κB-DNA binding at concentrations as low as 20 μM in binding reactions. The human lactoferrin (hLF) peptide is dissolved in phosphate buffer to a concentration of 0.1 mm. Reduction of the disulfide bonds is obtained by adding a 30-fold molar excess of TCEP hydrochloride with subsequent incubation for 2 h at 37 ℃.