Chemical Research in Toxicology of KWKK conjugated via γ-OH-PdG. These lesions block E. coli polymerases II, III, and V, but not polymerase IV. Cells deﬁcient in polymerase IV are ineﬃcient in replicating these lesions. It will now be of interest to determine the crystal structures of the complexes between the DNA KWKK conjugate and Y-family DNA poly- merases that bypass bulky minor groove lesions. ’ SUMMARY Treatment of an oligodeoxynucleotide containing a site- speciﬁc γ-OH-PdG lesion with excess peptide KWKK at neutral pH produced two stereoisomeric carbinolamine N2-dG:N-Lys DNA KWKK conjugates. In DNA, these conjugates exhibited lifetimes of weeks at neutral pH. Hydrolysis of the conjugates was accelerated by denaturation of the DNA. Upon hydrolysis of the peptides in the 50-CpX-30 sequence, N2-dG:N2-dG DNA inter- strand cross-links and ring-opened γ-OH-PdG derivatives ap- peared. Potential energy minimization, followed by MD simulations carried out in explicit solvent predict that the S-isomer is the major conjugate, probably due to the formation of an intramolecular hydrogen bond. Molecular modeling sug- gests that the carbinolamine DNA KWKK conjugates exist with the peptide located in the minor groove. ’ ASSOCIATED CONTENT bS Supporting Information. Figures S1, gel ﬁltration of the reaction mixture by Sephadex G25; S2, MALDF-TOF MS of the DNA KWKK conjugates; S3, NOE connectivity of base aro- matic H6/H8 protons with deoxyribose H10 protons; S4, chemi- cal shift perturbations; S5, force constants used for the carbinolamine linkage; S6, molecular dynamics simulations of the R- and S-carbinolamine DNA KWKK. This material is available free of charge via the Internet at http://pubs.acs.org. ’ AUTHOR INFORMATION Corresponding Author *Tel: 615-322-2589. Fax: 615-322-7591. E-mail: michael.p. stone@vanderbilt.edu. 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