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Solid‐Phase Synthesis of a β 3 ‐Icosapeptide Containing the Homologs of the Twenty Common Proteinaceous Amino Acids. Preliminary Communication
Author(s) -
Kimmerlin Thierry,
Seebach Dieter
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390166
Subject(s) - chemistry , disulfide bond , aqueous solution , amphiphile , phase (matter) , amino acid , side chain , crystallography , salt (chemistry) , solid phase synthesis , stereochemistry , proton nmr , sequence (biology) , organic chemistry , peptide , copolymer , polymer , biochemistry
An icosapeptide, 1 , containing the β 3 ‐amino acid residues with the 20 proteinogenic side chains has been assembled by manual solid‐phase synthesis, according to the Fmoc strategy. The sequence was chosen in such a way that a possible 3 14 ‐helical conformation (secondary structure) would be stabilized by salt bridges and have an amphipathic character ( Fig. 1 , a ), and the N‐terminal β 3 hCys would lend itself to thioligations and disulfide formation ( 2 and 3 , in Figs. 1 and 2 ). The products 1 – 3 were pure according to RP‐HPLC, NMR, and MS analysis ( Fig. 1 , b and c, Fig. 2 , c and d , and Fig. 3 ). With due caution, the CD spectra in aqueous solution (pH 7) and in MeOH ( Fig. 4 ), with normalized Cotton effects θ =−14000 to −16000 [deg⋅cm 2 ⋅dmol −1 ] between 209 and 210 nm, might be taken as an evidence for the presence of 3 14 ‐helical conformations. An evaluation of the data from a 700‐MHz 2D‐NMR measurement of the disulfide 2 in CD 3 OH is in progress.