Synthesis, crystal structure, and coordination properties of a helical peptide having β-(3-pyridyl)-l-alanine and l-glutamic acid residues

C‐Terminal ‐Aib‐L–Leu‐OMe Segment Promotes Schellman Loop from α‐Peptides with Alternating L–Leu and Aib Residues in the Crystal State

“…However, this is not always the case. For example, about one half of helical peptides longer than pentamer and terminating with the ‐Aib‐Leu‐OMe sequence does give rise to a Schellman motif, while one half does not . Screw sense reversal of a C‐terminal Aib‐OMe moiety alone cannot give rise to a Schellman motif.…”

Decelerated chirality interconversion of an optically inactive 310-helical peptide by metal chelation

“…3d Oku and his co-workers have also demonstrated that a helical structure is stabilized by complexation with Co(II) ion. 9 However, a well-defined 3 10 -helical peptide with metal ligation to the side-chains has rarely been demonstrated.…”

“…5,11 We chose the same octapeptide we studied previously, Cbz-[Aib 2 -Api(Boc)] 2 -Aib 2 -OMe (Cbz = benzyloxycarbonyl; Api(Boc) = 1-Boc-piperidine-4-amino-4-carboxylic acid; Boc = tert-butoxycarbonyl; OMe = methoxy) (1), 7d as a rigid backbone to design the metal-ligating 3 10 -helical peptide. The high percentage of Aib residues in short peptides is known to show a strong preference for the 3 10 -helix, 5,[7][8][9][10][11] and the achiral Api residue possessing functional group at the side-chain is also known to promote the helical structure. 8,12 The peptide 1 was shown to adopt the 3 10 -helical structure in the crystalline and solution states.…”