Cyclic dodecapeptide

Modifications designed to enhance the enzyme resistance and prolong the activity of SS derivatives have been quite successful. The use of D-amino acids instead of the normal L-enantiomers (e.g., in Trp ), or replacement of the disulfide link by a nonreducible ethylene bridge, leads to an increased duration of activity, approaching 3 hours. Several analogs show a greatly increased effect, like the [D-Ala, D-Trp ]somatostatin, which has 20 times the activity of SS on growth hormone release. The NH-terminal outside the cyclic dodecapeptide is not essential for activity. Selectivity of action results from... 

Effect of /-Irradiation on Aqueous Solutions of the Cyclic Dodecapeptide Polymyxin B... 

An example of a solid-phase synthesis of a side chain-to-C-terminal cyclic peptide has also been published (Scheme 11). Lee et al. [78] exploited the side-chain resin attachment principle and Kates protocol to prepare bacitracin A, a cyclic dodecapeptide antibiotic, cycZo(H-A hi-Leu-DGlu-Ile-... 

D. Baron, L.G. Pease, E.R. Blout, Cation binding of a cyclic dodecapeptide cyclo-(L-Val-Gly-Gly-L-Pro)3 in an aprotic medium. J. Amer. Chem. Soc. 99 8299-8306 (1977)... 

Nogle, L.M., Marquez, B.L., and Gerwick, W.H. (2003) Wewakazole, a novel cyclic dodecapeptide from a Papua New Guinea Lyngbya majuscula. Org. Lett., 5, 3-6. 

After the reaction times given in Scheme 38, the respective couplings were quantitative according to chloranil and the Kaiser ninhydrin test and/or HPLC of small cleavage. The peak area of the crude Fmoc-deprotected dodecapeptide was 90% (HPLC k=214nm). The pure cyclic peptide was obtained in an overall yield of 31%. Cyclosporin O was synthesized by a similar procedure.129 ... 

Synthesis of the bicyclic dodecapeptide theonellamide F is achieved via cyclic peptide 224 which in turn is prepared from building block 223. The key intermediate 223 is prepared by coupling of tetrapeptide 221 and a p-alanine derivative (222).83... 

Misumi, S., Takamune, N., Ido, Y., Hayashi, S., Endo, M., Mukai, R., Tachibana, K., Umeda, M. and Shoji, S., 2001a, Evidence as a HIV-l self-defense vaccine of cyclic chimeric dodecapeptide warped from undecapeptidyl arch of exracellular loop 2 in both CCR5 and CXCR4. Biochem. Biophys. Res. Commun. 285 1309-1316. 

While all peptide nanotubes considered thus far have fairly small pores (up to 13 A van der Waals diameter for cyclic D,L-a-dodecapeptides " ), nanotubes in a completely... 

Two chains of dodecapeptides were connected to a cyclic octapeptide in a parallel (F12-C8KL) or an antiparallel orientation (CH2). In principle, the dodecapeptides were designed to take an amphiphilic a -helical structure, which promotes association of the peptides in water. 

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