208262-74-2Relevant academic research and scientific papers
The N-terminal nonapeptide of cephaibols A and C: A naturally occurring example of mismatched helical screw-sense control
Orcel, Ugo,De Poli, Matteo,De Zotti, Marta,Clayden, Jonathan
, p. 16357 - 16365 (2013)
The N-terminal nonapeptide domain of the fungal nonribosomal peptide antibiotics cephaibol A and cephaibol C (AcPheAib4LeuIvaGly- Aib) is reported to adopt a right-handed helical conformation in the crystalline state. However, this conformation is at odds with the left-handed helicity observed in solution in related synthetic oligomers capped with Ac-L-PheAib4 fragments. We report the synthesis of four diastereoisomers of the cephaibol N-terminal nonapeptide, and show by NMR and CD spectroscopy that the peptide containing the chiral amino acids Phe and Leu in the naturally occurring relative configuration exists in solution as an interconverting mixture of helical screw-sense conformers. In contrast, the nonapeptide containing the unnatural relative configuration at Phe and Leu adopts a single, stable helical screw-sense, which is left handed when the N-terminal Phe residue is L and right-handed when the N-terminal Phe residue is D.
Induction of unexpected left-handed helicity by an N-terminal L -amino acid in an otherwise achiral peptide chain
Brown, Robert A.,Marcelli, Tommaso,Depoli, Matteo,Sola, Jordi,Clayden, Jonathan
supporting information; experimental part, p. 1395 - 1399 (2012/03/27)
Peptide helices containing L-amino acids are typically right-handed. Exceptions are peptide helices containing the achiral amino acids 2-aminoisobutyric acid and glycine with a single chiral amino acid at the Nterminus. These helices are left-handed when the N-terminal residue is a common tertiary proteinogenic amino acid, such as L-valine (see picture, left), but right-handed when the N-terminal residue is the quaternary amino acid L-α-methylvaline (right). Copyright
