Supplemental Information for: Human Replication Protein A, Rad52, ssDNA Complex: Stoichiometry and Evidence for Strand Transfer Regulation by Phosphorylation

Protein Purification, and ssDNA. RPA was purified as described previously with the following modification. Bacterial cultures expressing recombinant RPA were supplemented with 100 μM ZnCl2. The protein concentrations were calculated using a Bradford assay (BioRAD) with bovine serum albumin as a standard. These values were verified using a NanoDrop spectrophotometer and extinction coefficient of 8.8 X 10 Mcm (1) at 280 nm for RPA. Purified RPA was dialyzed into 1X PBS, 0.5% inositol, 2 mM EDTA and 2 mM 2-mercaptoethanol. The 3’ biotinylated synthetic 25-mer mixed oligonucleotide (MW 7815) was the same oligonucleotide used in the main paper. Biotinylated oligonucleotide was dissolved in water and the concentration was measured at OD260 using an extinction coefficient of 4.21 nMcm.