Synthesis and conformational analysis of (alpha Me)Leu/Aib model peptides.
We have synthesized by solution methods and fully characterized a variety of (alpha Me)Leu/Aib model peptides to the octapeptide level. A solution conformational analysis was performed by using infrared absorption. 1H nuclear magnetic resonance, and circular dichroism. The crystal-state structures of Z-D-(alpha Me)Leu-(Aib)2-OtBu, pBrBz-(Aib)2-D-(alpha Me)Leu-(Aib)2-OtBu, and Ac-(Aib)2-D-(alpha Me)Leu-(Aib)2-OtBu monohydrate were solved by x-ray diffraction. The results indicate that the (alpha Me)Leu residue may be easily incorporated into beta-bends and 3(10)-helical structures, and suggest that this residue tends to induce a helix handedness opposite to that promoted by its unmethylated counterpart (Leu) of the same optical configuration.
Pantano
M
M
Biopolymer Research Center, C.N.R. Department of Organic Chemistry, University of Padova, Italy.
Formaggio
F
F
Crisma
M
M
Bonora
G M
GM
Toniolo
C
C
Aubry
A
A
Bayeul
D
D
Dautant
A
A
Précigoux
G
G
Boesten
W H
WH
D000621:Aminoisobutyric Acids; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D007930:Leucine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000138:chemical synthesis*; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared
D000621:Aminoisobutyric Acids; D010455:Peptides; C100049:2-aminoisobutyric acid; D007930:Leucine