We have synthesized by solution methods and fully characterized a variety of (alphaMe)Leu/Aib model peptides to the octapeptide level. A solution conformational analysis was performed by using infrared absorption, H-1 nuclear magnetic resonance, and circular dichroism. The crystal-state structures of Z-D-(alphaMe)Leu-(Aib)2-OtBu, pBrBZ-(Aib)2-D-(alphaMe)Leu-(Aib)2-OtBu, and Ac-(Aib)5-D-(alphaMe)Leu-(Aib)2-OtBu monohydrate were solved by x-ray diffraction. The results indicate that the (alphaMe)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.
Synthesis and Conformational-analysis of (alpha-me)leu Aib Model Peptides
FORMAGGIO, FERNANDO;TONIOLO, CLAUDIO;
1993
Abstract
We have synthesized by solution methods and fully characterized a variety of (alphaMe)Leu/Aib model peptides to the octapeptide level. A solution conformational analysis was performed by using infrared absorption, H-1 nuclear magnetic resonance, and circular dichroism. The crystal-state structures of Z-D-(alphaMe)Leu-(Aib)2-OtBu, pBrBZ-(Aib)2-D-(alphaMe)Leu-(Aib)2-OtBu, and Ac-(Aib)5-D-(alphaMe)Leu-(Aib)2-OtBu monohydrate were solved by x-ray diffraction. The results indicate that the (alphaMe)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.
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