Figure 4.

Site transfer probabilities and kinetic activity of hUNG in the presence of variable cosolutes. (A) Phosphorimages of the products derived from reaction of hUNG with two 90mer substrates (S5^U and S20^U) with two uracil residues spaced 5 (black) and 20bp (red) apart. Solution conditions and co-solutes are indicated under each lane of the gel images. The P_trans values for S5^U reflect directional bias as indicated by the low population of the single excision AB fragment (see text and Supplemental Information). (B) The transfer probabilities between uracil sites in S5^U and S20^U in the presence of various co-solutes at 22 (red) and 150 mM salt (black) (T = 37°C). The P_trans values for S5^U at 150 mM salt represent unidirectional site transfer from site 2 to site 1 (P_trans^2→1). (C) Effects of salt, 20% PEG 8K, and salDNA on the observed rate of 8-oxoG excision from S20^U. P_trans and reaction rate data for 22 mM K⁺ in the presence of 20% PEG 8K has been published and is shown here for comparison⁹. Error is derived from 3 independent trials of each condition.