TITLE:
Use of a Mid-Infrared Free-Electron Laser (MIR-FEL) for Dissociation of the Amyloid Fibril Aggregates of a Peptide
AUTHORS:
Takayasu Kawasaki, Takayuki Imai, Koichi Tsukiyama
KEYWORDS:
Amyloid Fibrils; Amyloidosis; Free-Electron Laser; Amide I Band; β-Sheet
JOURNAL NAME:
Journal of Analytical Sciences, Methods and Instrumentation,
Vol.4 No.1,
March
11,
2014
ABSTRACT: Amyloid fibrils are deposited in various
tissues in the body, and are linked to the putative causes of serious diseases
such as amyloidosis. Although the conditions of the disease would be expected
to improve if the fibril structure could be destroyed, the aggregated structure
is stable under physiological conditions. Recently, we found that the amyloid
fibrils of lysozyme could be refolded into their active form by using a
mid-infrared free-electron laser (MIR-FEL) tuned to the amide I band
(corresponding to the C=O stretch vibration), with the MIR-FEL having specific
oscillation characteristics of a picosecond pulse structure, a tunable
wavelength within mid-infrared frequencies, and high photon density. In the
study, we tested the usability of the FEL for dissociation of aggregates of
pathological amyloid fibrils by using a short peptide of human thyroid hormone.
The fibrils (after being placed on a glass slide) were irradiated using the FEL
tuned to the amide I band (1644 cm?1), and those in situ were
analyzed by Congo-Red assay, scanning-electron microscopy, and
transmission-electron microscopy. All of the results obtained using these
microscopic analyses indicated that the amyloid fibril formation was
considerably decreased by FEL irradiation. Moreover, upon irradiation, a strong
fibril peak at the amide I band in the infrared spectrum was transformed into a
broad peak. These results imply that the β-sheet-rich structure of the
amyloid fibrils changed into non-ordered or unspecified structures after the
FEL irradiation. This FEL irradiation system, combined with various analytical
methods, shows promise for the dissociation of amyloid aggregates.