Crystallographic characterization of tryptophan-containing peptide 3(10)-helices.
The molecular and crystal structures of four peptides containing one L-Trp guest residue in Aib (alpha-aminoisobutyric acid or C alpha-methyl alanine) host oligopeptide chains have been determined by X-ray diffraction. The peptides are Z-Aib-L-Trp-Aib-OMe, Z-(Aib)2-L-Trp-Aib-OMe, Z-(Aib)3-L-Trp-Aib-OtBu and Boc-(Aib)3-L-Trp-Aib-OMe. Right-handed beta-turns and incipient and fully developed 3(10)-helices are formed in the crystal state by the tri-, tetra- and pentapeptides, respectively. The Trp residue is easily accommodated in these folded structures. The average geometry and preferred conformation for the Trp indolyl side chain are also discussed.
George
C
C
Naval Research Laboratory, Washington, DC, USA.
Flippen-Anderson
J L
JL
Bianco
A
A
Crisma
M
M
Formaggio
F
F
Toniolo
C
C
D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014364:Tryptophan / Q000737:chemistry*
D009842:Oligopeptides; D014364:Tryptophan