Standard reaction mixtures contained 5 μg DNA, 60 μg BSA, 25 mM MES (pH 6.0) or 25 mM MOPS (pH 7.0), 1 mM Asc and 0 or 100 μM Cr(VI). Data are means ±SD (n=3). Where not seen, error bars were smaller than symbols. (A) Time-course of DNA-BSA crosslinking. (B) DPC formation as a function of BSA concentration (reaction time =3 hr, MES buffer). (C) Importance of the initial reaction period in the DPC production (0 – 180 min, DNA was added before the start of Cr(VI) reduction; 5 – 180 min, DNA was added 5 min after the start of Cr(VI) reduction).