Very short peptides with stable folds: building on the interrelationship of Trp/Trp, Trp/cation, and Trp/backbone-amide interaction geometries.

ABSTRACT: By combining a favorable turn sequence with a turn flanking Trp/Trp interaction and a C-terminal H-bonding interaction between a backbone amide and an i-2 Trp ring, a particularly stable (DeltaG(U) > 7 kJ/mol) truncated hairpin, Ac-WI-(D-Pro-D-Asn)-KWTG-NH(2), results. In this construct and others with a W-(4-residue turn)-W motif in severely truncated hairpins, the C-terminal Trp is the edge residue in a well-defined face-to-edge (FtE) aryl/aryl interaction. Longer hairpins and those with six-residue turns retain the reversed "edge-to-face" (EtF) Trp/Trp geometry first observed for the trpzip peptides. Mutational studies suggest that the W-(4-residue turn)-W interaction provides at least 3 kJ/mol of stabilization in excess of that due to the greater beta-propensity of Trp. The pi-cation,

SUBMITTER: Eidenschink L 

PROVIDER: S-EPMC2656586 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature