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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster 1

CPP 12.5: Poster

Montag, 5. September 2022, 18:00–20:00, P1

F-Actin photocleavage as an artificial secondary nucleation model — •Stephan Sydow, Tobias Thalheim, Jörg Schnauß, and Frank Cichos — Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, Germany.

The aggregation of soluble proteins into highly ordered, insoluble amyloid fibrils is characteristic for a range of neurodegenerative disorders, like Alzheimer's or Parkinson's disease. The kinetics in the formation of amyloid fibrils are governed by multiple aggregation mechanisms, which are present simultaneously. One of these being the unspecific spontaneous breaking of Amyloid fibrils, whose cause, rate and break size distribution are still unknown, due to them being hidden in ensemble measurements.

We employ an artificial model system with a controllable fragmentation rate to compare it with current amyloid kinetic models, all assuming a homogeneous break size distribution. Fluorescence labelled Actin filaments exhibit photocleavage. By laser illumination of single, homogeneously labelled filaments in solution, we are able to control the breakage rate. The length and position of filaments and fragments are imaged over time by fluorescence microscopy.

We show, that Actin filaments exhibit a homogeneous break size distribution, verifying our artificial model system. Additionally, the fragment size distribution is independent of the intensity dependent, induced cleavage rate, thus it enables the direct comparison to current amyloid models.