The chemical steps of hOGG1 catalysis.

<p>Step 1: oxoG-base removal and formation of abasic product, step 2: β-elimination of 3′-phosphate resulting in formation of the nicked product.</p

Sequences of oligodeoxynucleotides used in this work.

<p>*aPu, 2-aminopurine; oxoG, 7,8-dihydro-8-oxoguanosine.</p

Stopped-flow fluorescence traces for interactions of hOGG1 with G-ligand.

<p>Changes in aPu fluorescence intensity during interaction of hOGG1 with G-ligand at different concentrations of enzyme at 25°C (A) and at different temperatures (B). Solid lines represent the fitted curves. The concentrations of hOGG1 and G-ligand were 2.0 µM and 1.0 µM, respectively. (C) Van’t Hoff analysis of the temperature dependence of <i>K</i>i for G-ligand.</p

Kinetic mechanism of hOGG1 processing of the oxoG-substrate.

<p>Here E is hOGG1; OG is the oxoG-substrate; (E•OG)_n are different enzyme-substrate recognition complexes; E•AP is the complex of E with the abasic site formed in the course of N-glycosylase reaction; E•P is the enzyme-product complex formed in the AP-lyase reaction; P is the final free reaction product; <i>k</i>_i and <i>k</i>_–i are the rate constants of the forward and backward individual processes.</p

Thermodynamic parameters of hOGG1 interactions with oxoG-substrate^a.

a<p>The errors indicated are ±1 SD. The errors for the Gibbs Energies, δ(Δ<i>G</i>°_i298) = RT(Δ<i>K</i>i/<i>K</i>i) ≤0.1 kcal/mol.</p

Van’t Hoff analysis of the temperature dependence of <i>K</i>i for oxoG-substrate.

<p>Van’t Hoff analysis of the temperature dependence of <i>K</i>i for oxoG-substrate.</p

Stopped-flow fluorescence traces for interactions of hOGG1 with oxoG-substrate.

<p>Changes in aPu fluorescence intensity during interaction of hOGG1 with oxoG-substrate at different concentrations of enzyme at 25°C (A) and at different temperatures (B). Solid lines represent the fitted curves. The kinetics of the accumulation of the abasic (C) and nicked (D) products, formed in the N-glycosylase and AP-lyase reactions, respectively, as detected in the PAGE experiments. The concentrations of hOGG1 and DNA for (B), (C) and (D) panels were 2.0 µM and 1.0 µM, respectively.</p