C. Peggion et al., (alpha Me)Aun: a highly lipophilic, chiral, C-alpha-tetrasubstituted alpha-amino acid. Incorporation into model peptides and preferred conformation, J PEPT RES, 55(3), 2000, pp. 262-269
Using a chemo-enzymatic approach we prepared the highly lipophilic, chiral,
C-alpha-methylated alpha-amino acid (alpha Me)Aun. Two series of terminall
y protected model peptides containing either D-(alpha Me)Aun in combination
with Aib or L-(alpha Me)Aun in combination with Gly were synthesized using
solution methods and fully characterized. A detailed solution conformation
al analysis, based on FT-IR absorption,H-1 NMR and CD techniques, allowed u
s to determine the preferred conformation of this amino acid and the relati
onship between chirality at its alpha-carbon atom and screw sense of the he
lix that is formed. The results obtained strongly support the view that D-(
alpha Me)Aun favors the formation of the left-handed 3(10)-helical conforma
tion.