NMR Studies On The Solution Structure Of Two β-peptides

Compared to other types of peptides,βpeptides have some novel physiological properties, they are not susceptible to proteolysis and metabolism, and have been shown to adopt three types of well-defined secondary structure (i.e., helix,sheet and turn) in solution.βpeptides provide an interesting alternative to structures and functions of natural peptides for design purpose. Because of these advantages,βpeptides stand out in the peptidomimetic compounds and attract considerable attention in biochemistry,biology,pharmacology and even in medicine areas.The ability of shortβpeptides to form stable secondary structure has been reported. Hexamer could fold into stable helical conformation in solution and shortβpeptide have more potential to study the stability and folding mechanism. In recent years small peptides have become the research emphases ofβpeptides. As a mainly experimental technique to analyze peptides, Nuclear Magnetic Resonance (NMR) possesses superiorities over other technologies.Here we studied twoβhexamer samples,6T1 and 6T2, which were specially designed to investigate the influences of side chains on the stability of theβpeptide's secondary structure. We determined the secondary structure of two peptides through constraint information of NOEs and hydrogen bonds detected by NMR and reported the influences of various side chains with spatial proximity on hydrogen bonding mechanism and helical secondary structure. The structure-stabilizing effects of the interactions between hydroxy,thiophene and amide groups have been discussed. The stability of theβpeptide's helical conformation in solution and the sensitivity of that to side chains compositions have been proved in this study.