Aggregation and Oligomerization Characterization of ß-lactoglobulin
Protein by a Solid State Nanopore Sensor
Abstract
This work demonstrates protein aggregation and oligomerization can be
evaluated by solid-state nanopore method. A silicon nitride nanopore
sensor is used to characterize a model protein ß-lactoglobulin variant A
(βLGa) amyloid formation and native-state oligomerization in close to
biological solution condition at single molecule level. To verify the
results obtained from nanopore measurements, atomic force microscopy
(AFM) and dynamic light scattering (DLS) techniques are used to measure
and calibrate the same βLGa protein samples incubated at different
stages. Using the parameters measured by DLS, AFM, and by measuring
linear and circular dsDNA molecules in the same nanopore, we estimate
the length and diameter of amyloid fibrils, and the number of βLGa
aggregation and the distribution of these species. Furthermore, as a
demonstration of the nanopore technique, βLGa self-association and
aggregation at pH 4.6 as a function of temperature are measured in 2M
and 0.1M salt. Protein aggregation has been linked to many chronic and
devastating neurodegenerative human diseases and is also strongly
associated with aging. This study shows the advantages and limitations
of evaluating protein aggregation by solid-state nanopore technology.