C O M M U N I C A T I O N S Acknowledgment. We thank B. Meade for critical input. This work was supported by a Specialized Center of Research (SCOR) grant from the Leukemia & Lymphoma Society, the California Institute for Regenerative Medicine, a grant from an anonymous donor, and the Howard Hughes Medical Institute (all to S.F.D.). Supporting Information Available: Detailed monomer and peptide synthesis and puriﬁcation methods; experimental methods; and Scheme S1. This material is available free of charge via the Internet at http:// pubs.acs.org. References (1) Nakase, I.; Niwa, M.; Takeuchi, T.; Sonomura, K.; Kawabata, N.; Koike, Y.; et al. Mol. Ther. 2004, 10, 1011–1022. (2) Wadia, J. S.; Stan, R. V.; Dowdy, S. F. Nat. Med. 2004, 10, 310–315. (3) Kaplan, I. M.; Wadia, J. S.; Dowdy, S. F. J. Controlled Release 2005, 102, 247–253. (4) Gump, J. M.; Dowdy, S. F. Trends Mol. Med. 2007, 13, 443–448. (5) Nakase, I.; Takeuchi, T.; Tanaka, G.; Futaki, S. AdV. Drug DeliVery ReV. 2008, 60, 598–607. (6) Gump, J. M.; June, R. K.; Dowdy, S. F. J. Biol. Chem. 2010, 285, 1500– 1507. (7) Shaughnessy, L. M.; Hoppe, A. D.; Christensen, K. A.; Swanson, J. A. Cell Microbiol. 2006, 8, 781–792. (8) Tsang, A. W.; Oestergaard, K.; Myers, J. T.; Swanson, J. A. J. Leuk. Biol. 2000, 68, 487–494. (9) IUPAC, Pure Appl. Chem. 1982, 54, 2693–2758. (10) Boonyarattanakalin, S.; Athavankar, S.; Sun, Q.; Peterson, B. R. J. Am. Chem. Soc. 2006, 128, 386–387. (11) Goldsmith, C. R.; Jaworski, J.; Sheng, M.; Lippard, S. J. J. Am. Chem. Soc. 2006, 128, 418–419. (12) Hussein, W. M.; Ross, B. P.; Landsberg, M. J.; Levy, D.; Hankamer, B.; McGeary, R. P. J. Org. Chem. 2009, 74, 1473–1479. (13) Kim, S. H.; Jeyakumar, M.; Katzenellenbogen, J. A. J. Am. Chem. Soc. 2007, 129, 13254–13264. (14) Lata, S.; Reichel, A.; Brock, R.; Tampe, R.; Piehler, J. J. Am. Chem. Soc. 2005, 127, 10205–10215. (15) Crowe, J.; Dobeli, H.; Gentz, R.; Hochuli, E.; Stuber, D.; Henco, K. Methods Mol. Biol. 1994, 31, 371–387. (16) Morgan, J. R.; Lyon, R. P.; Maeda, D. Y.; Zebala, J. A. Nucleic Acids Res. 2008, 36, 3522–3530. (17) Cooper, W. J.; Waters, M. L. Org. Lett. 2005, 7, 3825–3828. (18) Schwarze, S. R.; Ho, A.; Vocero-Akbani, A.; Dowdy, S. F. Science 1999, 285, 1569–1572. (19) Safran, M.; Kim, W. Y.; Kung, A. L.; Horner, J. W.; DePinho, R. A.; Kaelin, W. G. Mol. Imaging 2003, 2, 297–302. JA1040418 10682 J. AM. CHEM. SOC. 9 VOL. 132, NO. 31, 2010