Aza-peptides. III. Experimental structural analysis of aza-alanine and aza-asparagine-containing peptides.
To determine the structural perturbations induced by the C alpha H-->N alpha exchange in aza-peptides, we have examined by 1H NMR and IR spectroscopy various derivatives of the aza-analogues of alanine, aspartic acid and asparagine in different organic solvents with increasing polarity. Their general formulas are: R1-AzXaa-NR2R3, R1-Pro-AzXaa-NR2R3 and R1-AzXaa-Pro-NR2R3 (where AzXaa denotes the aza-analogue of the amino acid residue Xaa = Ala, Asp, Asn; R1 = Boc, Z; R2, R3 = H, Me, iPr). The aza-analogue of an amino acid residue appears to be a strong beta-turn-inducing motif, and the AzAsn carboxamide side-chain is capable of interacting, as a proton donor, with the preceding peptide carbonyl group.
André
F
F
LCPM, CNRS-URA-494, ENSIC-INPL, Nancy, France.
Vicherat
A
A
Boussard
G
G
Aubry
A
A
Marraud
M
M
D000409:Alanine / Q000737:chemistry*; D001216:Asparagine / Q000737:chemistry*; D001372:Aza Compounds / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
D001372:Aza Compounds; D010455:Peptides; D001216:Asparagine; D000409:Alanine