γ-Turn conformation induced by α,α-disubstituted amino acids with a cyclic six-membered side chain
1995; Elsevier BV; Volume: 51; Issue: 8 Linguagem: Inglês
10.1016/0040-4020(94)01095-h
ISSN1464-5416
AutoresMario Paglialunga Paradisi, Ines Torrini, Giampiero Pagani Zecchini, Gino Lucente, E. Gavuzzo, Fernando Mazza, G. Pochetti,
Tópico(s)Crystal structures of chemical compounds
Resumo4-Aminotetrahydrothiopyran-4-carboxylic acid (Thp) is an unusual achiral cyclic α,α-disubstituted amino acid mimicking the natural Met residue. The conformational energy map computed for Ac-Thp-NHMe shows that the γ-turn is the lowest minimum. 1H-NMR and IR studies performed on For-Thp-Leu-OMe (2a), a short peptide unable to give a 4…>1 H-bond, indicate that the γ-turn is adopted in CDCl3 solution, whereas is not retained in (CD3)2SO. An analogous conformational behaviour in solution has been observed for the strictly related For-Ac6c-Leu-OMe (2b), containing 1-aminocyclohexane carboxylic acid (Ac6c).
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