Figure 2.

Purification of CUP by binding site oligonucleotide affinity chromatography. (A) CUP purified by chromatography on DNA-cellulose was applied to a CUP-1 binding site oligonucleotide-Sepharose column, and elution was performed with a KCl gradient (□). CUP binding activity (•) in the eluted fractions was monitored by quantitative EMSA. (B) 50 μl of selected fractions were subjected to SDS/PAGE, after which the gels were silver-stained. W_f refers to final wash of the column, S refers to starting material (derived from the pooled fractions from DNA-cellulose chromatography), F refers to the flow-through volume of the CUP-1 binding site affinity column, and STD refers to molecular mass standards. The arrow identifies the 50-kDa band.