Conformational preferences of oligopeptides rich in alpha-aminoisobutyric acid. I. Observation of a 3(10)/alpha-helical transition upon sequence permutation.
The solution conformation of peptides rich in the alpha, alpha-dialkylated amino acid Aib has proven to be a subtle problem, not because of helix/coil transitions, but rather because of alpha-helical/3(10)-helical competition. A special series of peptides containing 75% Aib has been synthesized that feature identical amino acid composition but differing sequences; they are sequence permutation isomers. Nuclear magnetic resonance hydrogen-bonding studies reveal that there is a sequence permutation induced transition between the two alternative helical forms within this set. The implications for the design and conformational prediction of helical Aib-rich peptides are discussed.
Basu
G
G
Cornell University, Department of Chemistry, Baker Laboratory, Ithaca, New York 14853.
Bagchi
K
K
Kuki
A
A
D000595:Amino Acid Sequence; D000621:Aminoisobutyric Acids; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation
D000621:Aminoisobutyric Acids; D009842:Oligopeptides; C100049:2-aminoisobutyric acid