Confocal Fluorescence Detected Linear Dichroism Imaging of Isolated Human Amyloid Fibrils. Role of Supercoiling

摘要: Amyloids are highly organized insoluble protein aggregates that associated with a large variety of degenerative diseases. In this work, we investigated the anisotropic architecture isolated human amyloid samples stained Congo Red. This was performed by fluorescence detected linear dichroism (FDLD) imaging in laser scanning confocal microscope equipped differential polarization attachment using high frequency modulation state beam and demodulation circuit. Two- three-dimensional FDLD images amyloids provided information on orientation electric transition dipoles intercalated Red molecules unprecedented precision spatial resolution. We show that, accordance (Jin et al. Proc Natl Acad Sci USA 100:15294, 2003), exhibit strong anisotropy preferential dye along fibrils; estimations angle, around 45°, given model calculation which takes into account helical organization filaments fibrils. Our data also display inhomogeneities, local values alternating signs and, some regions, well identifiable µm-sized periodicities. These features accounted for supercoiling helically