Buffer D (TFIID)

0.1 mM EDTA

20% glycerol (v/v)

20 mM HEPES-KOH (pH 7.9)

KCl (0 M, 0.1 M, 0.2 M, 0.25 M, 0.5 M, or 0.85 M)

1 mM PMSF (phenylmethylsulfonyl fluoride)

Prepare separate batches of buffer D (TFIID) containing the following concentrations of KCl: 0 M (no added KCl), 0.1 M, 0.25 M, 0.5 M, 0.85 M, and 1.0 M. In each case, prepare the salt solutions in advance and add the PMSF just before use.