Figure 2.

Chemistry of substrate fragment tethering. In this approach, a suitable substrate fragment (such as uracil) is identified and derivatized at a nonperturbing position with an aldehyde functional group. In the case of UNG2, the substrate fragment ii 6-formyluracil. The substrate fragment is tethered to one end of a bifunctional alkyloxyamine linker of variable length (n = 2–6), which is then derivatized on the other end with a library of aldehyde binding elements (RCHO). Although statistical mixtures of all possible oximes result (25% each homodimer derived from uracil-CHO or RCHO, and 50% of the heterodimer derived from uracil-CHO and RCHO), this poses no difficulty because the crude mixtures are directly screened for inhibitory activity. Once active mixtures are identified, the specific inhibitory components can be rapidly identified by deconvolution to uncover the linker length that gave rise to the observed inhibition. The structures of the 215 aldehyde library members used in this study are reported in Supplementary Table S1.