Figure 1.

Purification of DNA-binding proteins from pea mitochondria. A, Purification scheme. Pea mitochondria were denatured by boiling in an SDS-containing buffer. The SDS-lysate was loaded onto a hydroxyapatite column and eluted with a linear NaPO₄ gradient (0.1–0.5 m). Aliquots of the eluted fractions were renatured and tested for DNA-binding activity in mobility-shift experiments (B). Fractions with binding activity (nos. 22–28) were pooled, renatured, and loaded onto a phosphocellulose column. The column was eluted with a linear NaCl gradient (0.1–1 m), and fractions were assayed for DNA-binding activity by mobility-shift analysis (C). The approximate NaPO₄ and NaCl concentrations of fractions with the highest binding activities are indicated at the upper margins. Arrows in the right margins indicate the positions of the unbound ds-oligonucleotide P3 and of the DNA-protein complexes C1 and C2. Fraction numbers are given at the bottom in B and C.