Conformational and stability studies of novel b-peptides from L-aspartic acid and b-amino-L-alanine

ORGN 912

Kamaljit Kaur, kkaur@ualberta.ca1, Sahar Ahmed, sahmed@pharmacy.ualberta.ca1, Reem Beleid, rbeleid@pharmacy.ualberta.ca1, and Tara Sprules, tara.sprules@mcgill.ca2. (1) Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, 3126 Dentistry/Pharmacy Centre, Edmonton, AB T6G 2N8, Canada, (2) 2Quebec/Eastern Canada High Field NMR Centre, McGill University, Room 023 Pulp & Paper Research Centre, 3420 University St., Montreal, QC H3A 2A7, Canada
b-peptides, with an additional methylene group in the backbone compared to the natural alpha-peptides, are gaining recognition from biological and pharmaceutical standpoints. These peptidomimetics exhibit well-defined secondary structure and possess several other desirable characteristics such as high metabolic stability, long elimination half-lives, cell membrane permeability, and nonmutagenicity. We have recently reported the synthesis of novel b3- and b2-peptides from L-aspartic acid and b-amino L-alanine (L-diaminopropionic acid), respectively [Org. Lett. 2007, 25]. The synthetic methodology involves independent buildup of the peptide backbone and the introduction of sequential side-chain variations leading to a high level of synthetic versatility. Here we report the synthesis of several such b-peptides and their preferred solution conformation using NMR spectroscopy and molecular dynamics simulations. These peptides adopt helical structures in trifluoroethanol and b3-peptides seem to be more structured than the b2-peptides. The metabolic stability of these molecules toward various proteolytic enzymes will also be discussed.