Self-Assembly of Nicotinic Acid-Conjugated Selenopeptides into Mesotubes.

The study of controlling the morphology for designing advanced supramolecular architectures by tuning the molecular motif at the elemental level has been rarely carried out. Here, we report the synthesis of a nicotinic acid-conjugated selenopeptide, which induced the formation of an unbranched mesoscale elongated tubular morphology. We rationally designed two additional peptides to find out the decisive role played by the nitrogen atom (in nicotinic acid) and selenium (in the peptide backbone) toward the formation of the mesotube. We found that the peptide, devoid of nitrogen, forms a fibrillar structure, whereas the peptide without selenium self-assembled into a cylindrical filled rodlike morphology. Here, we report an entirely different class of peptide inspired from the selenopeptide chemistry that forms a tubular structure and unambiguously establish that both nicotinic acid and selenium are essential toward the formation of such mesotubes.

Facile synthesis of stable selenocystine peptides and their solution state NMR studies.

A facile general route for the synthesis of various selenocystine tripeptides containing acidic, basic and neutral side chain amino acids is reported. Here, TFA labile side chain protected selenocysteine has been used as a precursor for the synthesis of selenopeptides. The peptides are highly stable in dimethyl sulphoxide, thus enabling detailed NMR studies by solution phase 1- and 2-dimensional NMR spectroscopy.

Self-assembly of penta-selenopeptides into amyloid fibrils.

Here, we report the synthesis of a penta-selenopeptide consisting of five benzyl protected selenocysteine residues. This selenopeptide was well characterized by both one- and two-dimensional (D) NMR spectroscopies. We find that the solution conformation is enriched with ß-sheet structures, which have a propensity to self-assemble and form amyloid fibrils.