Azaproline as a beta-turn-inducer residue opposed to proline

• Published in: The journal of peptide research Vol. 52; no. 1; pp. 19 - 26
• Main Authors: Zouikri, M, Vicherat, A, Aubry, A, Marraud, M, Boussard, G
• Format: Journal Article
• Language: English
• Published: COPENHAGEN Wiley 01.07.1998
• Subjects: Aza Compounds - chemistry; Biochemical Research Methods; Biochemistry & Molecular Biology; Dimethyl Sulfoxide - pharmacology; Life Sciences & Biomedicine; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Conformation; Molecular Structure; Peptides - chemistry; Proline - analogs & derivatives; Protein Folding; Protein Structure, Secondary; Science & Technology; Stereoisomerism; MODEL DIPEPTIDES; ANALOGS; pseudopeptides; azapeptides; azaproline; HORMONE-RELEASING HORMONE; AMINO-ACID; azapeptide folding; PEPTIDES; HYDRAZINE COMPOUNDS; beta VI-turn; HETERO COMPONENTS; PSEUDOPEPTIDIC ERGOPEPTINES; ENZYME-INHIBITORS
• ISSN: 1397-002X
• DOI: 10.1111/j.1399-3011.1998.tb00648.x

Azaproline (AzPro) is an analogue of proline containing a nitrogen atom in place of the (CH)-H-alpha group. AzPro has been introduced in various model peptides, and especially in the BocAla-AzPro-Ala-NHiPr tripeptide. The structural consequence of that modification has been investigated in solution by using IR and H-1 NMR, with reference to the cognate proline-containing peptide. Contrary to proline, which induces beta-folding of the Pro-Ala sequence, azaproline apparently favors beta VI-folding of the Ala-AzPro one with high occurrence. Opening of the AzPro pyrazolidine ring to get N-methylazaalanine fundamentally does not change the structural properties of the azatripeptide, but allows the existence of open conformers to an extent depending on the solvent.