| The focus of the present research is the synthesis of polypeptides for the study of protein folding and misfolding and for the development of novel polypeptide-based optical antennas in nanotechnology. It is hypothesized that simple polypeptides can be used as models to mimic in vivo folding of globular proteins. Desired repetitive polypeptides were genetically encoded and expressed in E. coli using conventional methods and characterized using a variety of spectroscopic (including circular dichroism (CD), deep UV resonance Raman (DUVRR), UV-vis and fluorescence) and microscopic (atomic force microscopy (AFM) and transmission electron microscopy (TEM)) techniques. The polypeptides predominantly formed bilayer, fibrillar structures with a cross beta-core. YEHK21-YE8, a chimeric polypeptide, folded within three days. The folding/fibrillation of the chimeric construct illuminates the controlling factors and hence suggests the importance of those factors in amyloidogenic diseases. YE8 and YE8 derivatives illustrated the role of proline in beta-sheet formation. The EW polypeptide models elucidated the influence of tryptophan residues and the degree of polymerization on folding. The study of EW14C1 and EW21C1 demonstrated light-harvesting properties when labeled with a suitable dye. |
