Design and Syntheses of Gramicidin S Analogs, Cyclo(-X-Leu-XD
The Journal of Antibiotics (2011) 64, 583–585 & 2011 Japan Antibiotics Research Association All rights reserved 0021-8820/11 $32.00 www.nature.com/ja NOTE Design and syntheses of gramicidin S analogs, cyclo(-X-Leu-X-D-Phe-Pro-)2 (X¼His, Lys, Orn, Dab and Dap) Makoto Tamaki1, Kenta Fujinuma1, Takuji Harada1, Kazumasa Takanashi1, Mitsuno Shindo2, Masahiro Kimura2 and Yoshiki Uchida2 The Journal of Antibiotics (2011) 64, 583–585; doi:10.1038/ja.2011.43; published online 25 May 2011 Keywords: gramicidin S; polycationic analog; structure-activity relationship; synthesis 1,1¢ 2,2¢ 3,3¢ 4,4¢ 5,5¢ 1–3 Gramicidin S (GS), cyclo(-Val -Orn -Leu -D-Phe -Pro -)2, solid phase peptide synthesis on oxime resin (loading of oxime group: is a potent cyclopeptide antibiotic isolated from Bacillus brevis.Its 0.35 mmol gÀ1 resins) (Scheme 1).8 Yresidue(Y¼His(3-Bom), Lys(Z), secondary structure has been established as an antiparallel b-sheet Orn(Z), Dab(Z) and Dap(Z)) as a C-terminal amino acid residue was conformation with amphiphilicity.4,5 The conformation is charac- used based on the propensity of the biosynthetic precursor of GS teristically featured with the orientation of side chains in such a way to form a conformation highly favorable for head–tail cyclization.2,3 that the charged Orn side chains are situated on one side of the The cyclization-cleavage of H-D-Phe-Pro-Y-Leu-Y-D-Phe-Pro-Y-Leu- molecule and the hydrophobic Val and Leu side chains are situated on Y-oxime from the resin was performed in 1,4-dioxane with 2 equiv the other side.
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